Chemistry Exams All – Flashcards
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| Which of the following is a property of a solid? |
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| The particles have fixed positions and are very close together. |
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| If experimental results do not agree with your hypothesis, you should |
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| write a new hypothesis |
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| In an atom, the nucleus contains |
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| all the protons and neutrons |
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| Which element would have physical and chemical properties similar to chlorine? |
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| Br |
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| Almost all of the mass of an atom exists in its |
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| nucleus |
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| Au is the symbol for |
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| gold |
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| Air is a(n) |
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| homogeneous mixture |
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| The primary substances of which all other things are composed are |
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| elements |
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| Which of the following is an example of a hypothesis? |
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| Plants need sunlight to grow |
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| Isotopes are atoms of the same element that have |
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| the same atomic number but different number of neutrons |
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| which of the following is a characteristic of the modern periodic table? |
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| the elements in each group have similar chemical properties |
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| the atomic mass of an element is equal to |
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| a weights average mass of all of the naturally occurring isotopes of the element |
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| The electron arrangement of any particular atom shows |
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| the number of electrons in each shell |
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| what is the conversion factor for the relationship between millimeters and centimeters |
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| 10 mm/1cm |
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| the specific heat of copper is 0.093 cal/g C and the specific heat of silver is 0.057 cal/g C. if 100 cal of heat is added to one g of each metal at 25 C, what is the expected result |
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| the silver will reach a higher temperature |
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| A calculator answer of 423.6059 must be rounded off to three significant figures. what answer is reported |
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| 424 |
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| Mercury-202 has how many neutrons in its nucleus |
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| 122 |
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| the atomic number of an atom is equal to the number of |
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| protons |
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| the temperature of liquid nitrogen is -196 C. what is the corresponding reading on the kelvin scale |
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| 77 K |
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| a hypothetical element contains three isotopes of mass 16 amu, 17 amu, 18 amu with relative abundances of 20%, 50%, and 30% respectively. the average atomic mass is |
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| 17.1 amu |
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| what is the correct symbol for the element copper |
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| Cu |
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| how many calories are required to convert 17 g of ice at 0.0 C to liquid water at 32.0 C? the heat of fusion of water is 80 cal/g |
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| 1900 cal |
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| the number of dots in the electron dot structure of carbon is |
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| four |
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| if the temperature is 20 C what is the corresponding temperature on the Fahrenheit scale |
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| 68 F |
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| Which of the following is a measurement of mass in the metric system |
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| kilogram |
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| the correct answer for the addition of 7.5 g+2.26 g+1.311 g+2 g is |
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| 13 g |
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| in a gas the distance between the particles is |
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| very large relative to the size of the molecules |
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| the amount of space occupied by a substance is |
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| volume |
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| which of the following is an example of a physical change |
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| grinding coffee beans |
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| the formation of a gas resulting from the escape of high energy particles from the surface of a liquid is known as |
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| evaporation |
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| the cubic centimeter has the same volume as a |
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| millimeter |
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| diamond has a density of 3.52 g/mL what is the volume in cubic centimeters of a diamond with a mass of 15.1 g |
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| 4.29 cm3 |
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| 5.21 cm is the same distance as |
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| 0.0521 m |
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| which of the following gives the correct numbers of protons, neutrons, and electrons in a neutral atom of 118/50 Sn |
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| 50 protons, 68 neutrons, 50 electrons |
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| which of the following examples illustrates a number that is correctly rounded to three significant figures |
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| 20.0332 grams to 20.0 grams |
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| the energy associated with the motion of particles in a substance is called |
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| heat |
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| round the following number to 2 significant figures: 105.006 |
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| 110,000 |
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| two atoms must represent the same element if they both have the same: |
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| atomic number |
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| the specific heat of a substance is the amount of heat that is needed to |
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| raise the temperature of 1 g of the substance by 1C |
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| the physical state present when a substance is melting is |
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| solid+liquid |
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| in a covalently bonded molecule the number of electrons that an atom shares with others is usually equal to the number of electrons |
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| needed to give it a noble gas arrangement |
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| Avogadro's number is the number of |
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| particles in 1 mole of substance |
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| in an oxidation-reduction reaction the substance reduced always |
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| shows a gain of electrons |
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| the half life of a radioisotope is |
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| the time it takes for one-half of the sample to decay |
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| the correct name of the compound NCl3 is |
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| nitrogen trichloride |
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| how many moles of iron are present in 3.15*10^24 atoms of iron |
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| 5.23 moles |
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| the main interactions between molecules of hydrogen chloride are examples of |
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| dipole-dipole interactions |
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| the nuclear symbol of helium 4/2 He, is also the symbol for designating |
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| alpha particle |
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| the molar mass of C3H8O2 is |
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| 76.0 g |
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| which of the following polyatomic ions has a positive charge |
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| ammonium |
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| valence electrons are electrons located |
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| in the outermost energy level of an atom |
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| which of the following gives the balanced equation for this reaction Ca3(PO4)2+KNO3 |
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| 2K3PO4+3Ca(NO3)2-> Ca3(PO4)2+6KNO3 |
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| the correct formula for the compound formed from Mg and S is |
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| MgS |
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| how many valence electrons are in the electron-dot structure of H2O |
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| 8 |
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| the ability of an atom to attract the shared electrons in a covalent bond is its |
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| electronegativity |
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| a wooden object from a prehistoric site has a carbon-14 activity of 10 counts per minute (cpm) compared to 40 cpm for new wood. if carbon-14 has a half-life of 5730 years what is the age of the wood |
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| 11,500 years |
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| how many moles of water H2O are present in 75.0 g of H2O |
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| 4.17 moles |
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| which of the following represents the correct Lewis structure for Cl |
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| Cl=7 |
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| what is the symbol for the ion with 19 protons and 18 electrons |
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| K+ |
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| the nuclear reaction shown below is an example of what type of process? 220/88 Rn + 4/2 He> |
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| alpha emission |
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| how many electrons will chlorine gain or lose when it forms an ion |
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| gain 1 |
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| what is the coefficient of hydrogen H2 when the following equation is balanced Al2(SO4)3 + ?H2> |
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| 3 |
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| what is the ionic charge of an ion with 18 protons and 15 electrons |
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| 3+ |
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| Given the following equation what is the correct form of the conversion factor needed to convert the number of moles of O2 to the number of mole of Fe2O3 produced 2Fe2O3 (s)> |
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| 2 moles of Fe2O3/3 moles of O2 |
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| the shape of the carbon tetrachloride molecule is |
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| tetrahedral |
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| how many lone pairs of electrons are in the electron dot structure of H2O |
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| 2 |
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| an ionic compound |
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| has a net charge of zero |
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| the shape of the ammonia molecule (NH3) is |
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| pyramidal |
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| which one of the following elements forms two or more ions with different ionic charges |
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| Fe |
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| which of the following polyatomic ions has a 3- ionic charge |
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| phosphate |
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| a_____is the smallest neutral unit of two or more atoms held together by a covalent bond |
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| molecule |
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| in any balanced chemical equation the number of each type of atom on both sides of the equation is |
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| the same |
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| if the electronegativity difference between elements X and Y is 2.1 the bond between the elements X-Y is |
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| ionic |
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| the symbol 0/-1 e is a symbol used for an |
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| beta particle |
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| what is the formula of carbon tetraiodide |
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| CI4 |
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| which of the following correctly gives the best coefficients for the reaction below? N2+H2O |
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| 1,2,1,4 |
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| 0.100 mole of lithium weighs |
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| 0.694 g |
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| Which one of the following compounds contains an ion with a 3+ charge |
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| FeCl3 |
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| the water molecule has a dipole with the negative portion |
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| pointing toward the oxygen atom |
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| the octet rule indicates that |
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| atoms lose, gain, or share valence electrons to have 8 valence electrons |
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| what is the correct formula for iron (III) sulfide |
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| Fe2S3 |
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| the VSEPR theory allows us to determine the most favorable |
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| shape of a molecule |
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| what is the formula of a compound that contains Na+ and PO4 3- ions |
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| Na3PO4 |
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| the shape of the water molecule H2O is |
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| bent |
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| the main type of interaction between molecules of hydrogen H2 are |
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| dispersion forces |
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| which of the following types of radiation has the highest energy |
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| y-rays |
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| how many grams of Fe2O3 are there in 0.500 moles of Fe2O3 |
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| 79.8 g |
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| the ammonia molecule NH3 is |
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| a polar molecule with polar bonds |
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| the process in which a nucleus spontaneously breaks down by emitting radiation is known as |
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| radioactive decay |
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| what is oxidized and what is reduced in the following reaction 2AlBr3(s) |
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| Al is oxidized and Br2 is reduced |
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| when 3.05 moles of CH4 are mixed with 5.03 moles of O2 the limiting reactant is |
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| O2 |
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| one mole of particles of any substance contains how many particles |
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| 6.02*10^23 |
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| how many moles of carbon atoms are there in 0.500 mole of C2H6 |
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| 1.00 moles |
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| how many moles of neon occupy a volume of 14.3 L at STP |
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| 0.638 moles |
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| as you rise higher in Earth's atmosphere the atmospheric pressure |
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| decreases |
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| what is the molarity of a solution that contains 3.25 moles of NaNO3 in 250. mL of solution |
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| 13.0 M |
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| how many molecules of water H2O are present in 75.0 g of H2O |
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| 2.51*10^24 molecules |
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| the unit of 1 atmosphere used to describe the pressure of a gas is equal to |
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| 760 mmHg |
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| according to the kinetic theory of gases, a gas can be compressed much more than a liquid or solid because |
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| the particles of a gas are very far apart |
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| the solubility of KI is 50 g in 100 g of H2O at 20 C. if 110 grams of KI are added to 200 grams of H2O |
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| A saturated solution will form |
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| the mathematical expression of the ideal gas law is |
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| PV=nRT |
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| what is the volume of a 1.5 M KOH solution is needed to provide 3.0 moles of KOH |
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| 2.0 L |
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| oil does not dissolve in water because |
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| oil is nonpolar |
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| how many kcal are produced when 32.0 g of CH4 react CO2+2H2O+ 218kcal |
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| 436 kcal |
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| a gas contained in a steel tank has a pressure of 1.5 atm at a temperature of 320 K what will be the gas pressure when the temperature changes to 450 K |
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| 2.1 atm |
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| in the process known as osmosis_____moves through a semipermeable membrane into an are of ____concentration |
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| solvent; lower solvent |
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| in a solution, the solvent |
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| can be a solid, liquid, or gas |
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| in any balanced chemical equation the number of each type of atom on both sides of the equation is |
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| the same |
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| what is the concentration in m/m% of a solution prepared from 50.0g NaCl and 150.0 g of water |
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| 25.0% |
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| in this reaction what is the correct coefficient for sodium chloridePbCl2(s)+NaNO3(aq)> |
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| 2 |
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| the reaction of carbon with oxygen to produce carbon monoxide is an example of which class of reaction 2CO(g)> |
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| combination |
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| an equivalent is |
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| the amount of ion that carries 1 mole of electrical charge |
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| In an endothermic reaction |
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| energy is absorbed by the system |
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| the volume of a sample of gas initially at 25 C increases from 158 mL to 450 mL. what is the final temperature of the sample of gas if the pressure in the container is kept constant |
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| 576 C |
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| the temperature of a 500. mL sample of gas increases from 150. K to 350. K what is the final volume of the sample of gas if the pressure in the container is kept constant |
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| 1170 mL |
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| at STP what is the volume of 4.50 moles of nitrogen gas |
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| 101 L |
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| during the process of diluting a solution to a lower concentration |
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| the amount of solute does not change |
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| when 10.0 g of NH3 reacts the actual yield of N2 is 8.50 g. what is the percent yield 5N2(g)+6H2O(l)> |
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| 41.3% |
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| a gas sample contains 4.0 g of CH4 and 2.0 g of He. what is the volume of the sample at STP |
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| 17 L |
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| a reaction that releases energy as it occurs is classified as a |
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| exothermic reaction |
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| the atmospheric pressure in Denver, CO is 633 mmHg what is this pressure in atm |
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| 0.833 atm |
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| in water a substance that ionizes completely in solution is called a |
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| strong electrolyte |
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| What is the molar mass of Mg3(PO4)2, a substance formerly used in medicine as an antacid |
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| 262.9 g |
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| a hydrogen bond is |
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| an attraction between the hydrogen atom attached to N,O,or F and an N,O, or F atom |
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| what unit of temperature is used in gas law calculation |
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| Kelvin |
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| find the mass of AlCl3 that is produced when 25.0 grams of Al2O3 reacts with HCl according to the following equation 2AlCl3(aq)+3H2O(l)> |
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| 65.4 g |
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| the total pressure in a mixture of gases is equal to the partial pressure of |
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| all the gases added together |
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| H2(g)+ZnCl2(aq)> When 25.0 g of Zn reacts, how many L of H2 gas are formed at STP |
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| 8.56L |
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| a 1.20-L container contains 1.10 g of an unknown gas at STP. what is the molecular weight of the unknown gas |
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| 20.5 g/mole |
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| given the following equation what is the correct form of the conversion factor needed to convert the number of moles of O2 to the number of moles of Fe2O3 produced |
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| 2 moles of Fe2O3/ 3 moles of O2 |
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| the___is the minimum energy needed for the chemical reaction to begin |
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| activation energy |
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| a tank contains a mixture of helium, neon, and argon gas if the total pressure in the tank is 490 mmHg and the partial pressure of helium and argon are 215 mmHg and 102 mmHg respectively what is the partial pressure of neon |
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| 173 mmHg |
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| when solutions of KCl and Pb(NO3)2 are mixed a precipitate forms. which of the following is the balanced equation for the double replacement reaction that occurs |
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| 2KCl(aq)+PB(NO3)2(aq)->2 KNO3(aq)+PbCl2(s) |
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| in the kinetic molecular theory of gas behavior the assumption is made that gas molecules |
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| move rapidly in random directions |
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| The molar mass of potassium is |
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| 39.1 g |
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| when solutions of NaCl and AgNO3 are mixed |
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| a precipitate of AgCl forms |
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| when some of the sugar added to iced tea remains undissolved at the bottom of the glass the solution is |
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| saturated |
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| at STP temperature and pressure have a value of |
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| 273 K and 760 mmHg |
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| what is the molar mass of copper(II) sulfate, CuSO4 |
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| 159.6 g |
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| how many moles of iron are present in 3.15*10^24 atoms of iron |
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| 5.23 moles |
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| a catalyst is |
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| a substance that speeds up a reaction without being consumed in the reaction |
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| when a reaction is at equilibrium |
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| the forward and reverse reactions occur at the same rate |
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| the activation energy of a chemical reaction is the energy that |
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| initiates the reaction |
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| a chemical reaction has reached equilibrium when |
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| the rate of the forward reaction equals the rate of the reverse reaction |
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| in the following reaction what is the effect of adding more NO2 to the starting reaction mixture N2O4> |
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| it would increase the final quantity of products |
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| iron metal reacts with oxygen gas to produce iron (III) oxide what will be the effect of increasing the pressure of oxygen gas in a closed reaction vessel |
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| more iron oxide will be produced |
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| in the following reaction what is the effect on the direction of the reaction if more SO3 is added to the reaction mixture 2SO3> |
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| the equilibrium shifts to produce more reactants |
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| in the following reaction Kc is much less than 1. at equilibrium which of the following statements is true CO+Cl2> |
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| the concentration of reactants is much greater than the concentration of products |
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| the equilibrium constant for the production of carbon dioxide from carbon monoxide and oxygen is Kc=2*10^11. this means that the reaction mixture at equilibrium is likely to consist of |
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| mostly products |
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| which of the following equilibrium constants indicates the reaction that gives the smallest amount of product |
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| Kc=5*10^-10 |
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| the equilibrium for the reaction for the decomposition of PCl5 to chlorine and PCl3 is 0.042. If the equilibrium concentrations are PCl3=0.010M, Cl2=0.10M, what is the value of PCl5PCl3(g)+Cl2(g)> |
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| 0.024M |
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| the rate of any chemical reaction can be determined by observing |
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| the amount of products formed in a unit of time |
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| refrigerating perishable foods affects biochemical reactions y |
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| decreasing the rate of reactions affecting spoilage |
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| one metal that is used as a catalyst in a catalytic converter in an automobile is |
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| platinum |
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| a reaction that can proceed in either the forward or the reverse direction as written is called a _____reaction |
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| reversible |
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| for the equilibrium reaction of carbon dioxide with water what is the appropriate equation |
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| H2O+CO2>H2CO3 |
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| the reaction for the decomposition of PCl5 to chlorine and PCl3 is shown below.if the equilibrium concentrations are PCl5= 1.0M PCl3=0.10M, Cl2=0.10 M what is the value of the equilibrium constant?PCl3(g)+Cl2(g) |
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| 1.0*10^-2 |
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| What is the correct form for the equilibrium constant for this reaction H2g+F2g>2HFg |
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| HF^2 H2F2 |
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| In an exothermic reaction heat can be considered a |
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| product |
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| for the reaction of carbon with carbon dioxide to make carbon monoxide, the reaction is as follows. write the form of the Kc. C(s)+CO2(g)>2CO(g) |
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| Kc= CO^2/ CO2 |
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| For the following reaction the equilibrium constant Kc is 2.0 at a certain temperature if the concentration of both products is 0.10 M at equilibrium what is the concentration of the starting material NOBr? 2NOBr(g)>2NO(g)+Br2(g) |
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| 2.2*10^-2 |
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| For the following reaction the equilibrium constant Kc is 2.0 at a certain temperature bromine can be liquefied easily and removed from the reaction vessel as it is formed. if this is done how will it affect the equilibrium reaction 2NOBr(g)>2NO(g)+Br2(g) |
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| more products will be made as Br2 is removed |
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| according to the Arrhenius concept if NaOH were dissolved in water it would act as |
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| a base |
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| according to the Arrhenius concept if HNO3 were dissolved in water it would act as |
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| an acid |
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| the name given to an aqueous solution of HNO3 is |
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| nitric acid |
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| which one of the following is characteristic of a base |
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| has a slippery, soapy feel |
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| according to the Bronsted-Lowry definition |
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| a base is a proton acceptor |
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| identify the Bronsted-Lowry acid in the following reaction H2O+CO3>HCO3+OH |
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| H2O |
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| the name of Al(OH)3 is |
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| aluminum hydroxide |
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| which of the following statements correctly describes the hydronium-hydroxide balance in the given solution |
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| in bases OH- is greater than H3O+ |
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| For Kw the product of H3O and OH is |
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| 1.0*10^-14 |
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| what is the H3O in a solution with OH=1*10^-12 M |
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| 1*10^-2 M |
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| ammonium hydroxide is a weak base because |
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| it dissociates only slightly in water |
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| what is the pH of a solution with H3O=1*10^-9 |
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| 9.0 |
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| what is the pH of a solution with a solution with OH=1*10^-4 |
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| 10.0 |
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| in which of the following are the pH values arranged from the most basic to the most acidic |
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| 14,10,7,4,3,1 |
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| which of the following is the strongest acid |
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| HCl |
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| an acid and base react to form a salt and water in a _____reaction |
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| neutralization |
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| which of the following is the correctly balanced equation for the complete neutralization of H3PO4 with Ca(OH)2 |
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| 2H3PO4+3Ca(OH)2>Ca3(PO4)2+6H2O |
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| the normal blood pH is about |
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| 7.4 |
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| the function of a buffer is to |
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| maintain the pH of a solution |
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| a 25.0 mL sample H3PO4 requires 50.0 mL of 1.50 M NaOH for complete neutralization what is the molarity of the acidNa3PO4+3H2O |
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| 1.00 M |
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| The Ka for hydrofluoric acid is 7.2*10^-4 this means that HF is |
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| a weak acid |
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| in a sulfuric acid solution where the H2SO4 is .005 M what is the pH |
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| pH=2 |
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| when a piece of magnesium metal is added to hydrochloric acid what gas is produced |
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| hydrogen |
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| the salt made from a weak acid and a strong base should give a solution of |
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| pH>7 |
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| which of the following could be a buffer |
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| HF+NaF |
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| The neutralization reaction between Al(OH)3 and HNO3 produces the salt with the formula |
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| Al(NO3)3 |
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| Which of the following is correctly identified |
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| NaOH strong base |
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| the H3O of solution with pH=2 is |
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| 1*10^-2 M |
