Chemistry Test 2 Answers – Flashcards
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Sr(OH)2
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strontium hydroxide
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Which of these compounds is not a base NaOH CH3NH2 Zn(OH)2 HF
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HF
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What is the formula for the compound nitrogen monoxide?
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NO
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What is the formula for the compound tetraphosphorus decoxide
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P4O10
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What is the formula for the compound methane
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CH4
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What is the name of the acid whose formula is HI?
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Hydroiodic acid
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What is the formula for chlorous acid?
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HClO2
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What is the name of the acid whose formula is H2CO3?
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carbonic acid
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What is the formula for sulfurous acid?
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H2SO3
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What is the name of the covalent compound CCl4
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carbon tetra chloride
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What is the name of the covalent compound N2O5?
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dinitrogen pentoxide
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What is the name for the compound NO2
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nitrogen dioxide
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B2H6
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diboron hexahydride
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chemical formula for quartz
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SiO2
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How many oxygen atoms are in 2.80 g of quartz?
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number of O atoms = 5.62×1022 *find molar mass, divide 2.80 by molar mass. use avogadros number to get rid of moles. and multiply by 2
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What is the formula weight of Mg(NO3)2?
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148.3 amu
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Calculate the formula weight of ethanol, C2H5OH
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46.1 amu
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How much does one sucrose molecule weigh in grams? Express your answer with the appropriate units.
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mass of one molecule of sucrose = 5.68×10?22 g *342 g/mol, divided by avogadros number
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A certain ionic compound is made entirely of aluminum and oxygen.
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Al2O3
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What is the mass percentage of each element in the compound Al2O3
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52.9% and 47.1% find mollar mass. and divide
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Enter the subscripts for C, H, and O, respectively, separated by commas (e.g., 5,6,7).
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1,2,1 CH2O
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The molecular formula mass of this compound is 150 amu . What are the subscripts in the actual molecular formula? Enter the subscripts for C, H, and O, respectively, separated by commas (e.g., 5,6,7).
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5,10,5
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A hydrocarbon is a compound that contains mostly carbon and hydrogen. Calculate the percent composition (by mass) of the following hydrocarbon: C 5 H 12 . Enter the percentages of carbon and hydrogen numerically to four significant figures, separated by commas.
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83.2%, 16.8% mass percent=mass of element / mass of compound×100%
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A certain metal hydroxide, M(OH)2, contains 32.8% oxygen by mass. What is the identity of the metal M? Enter the full name of the element.
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copper Mass of oxygen32.8g moles of oxygen 2.05(/16) moles of hydrogen2.05(= in formula) mass of hydrogen 2.05g (*1) Mass of metal 65.15g (by difference from 100) moles of metal 1.03(O /2) so we have 1.03 moles of metal in 65.15 g mass of 1 mole = 63.56 g copper !!
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Give the empirical formula of dimethylmercury
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HgC2H6
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How many molecules are contained in a 7.75-g sample of dimethylmercury? Express your answer in molecules to three significant figures.
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2.02×1022 molecules
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What is the percentage of mercury (by mass) in the sample? Express your answer as a percent to four significant figures.
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mass percent of Hg = 86.96 %
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What is the empirical formula for the compound P4O6?
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P2O3
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How many grams of each element are in this sample? Enter the number of grams of carbon followed by the number of grams of hydrogen, separated by a comma (e.g., 30.0,70.0).
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mass of C, mass of H = 80.0,20.0 g
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How many moles of each element are in this sample? Enter the number of moles of carbon followed by the number of moles of hydrogen, separated by a comma.
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6.7,20
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How many moles of carbon, C, were in the original sample? Express your answer to three significant figures and include the appropriate units
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.183 mol
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How many moles of hydrogen, H, were in the original sample? Express your answer to three significant figures and include the appropriate units.
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.367 mol
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If 5.50 g of the unknown compound contained 0.183 mol of C and 0.367 mol of H, how many moles of oxygen, O, were in the sample?
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.183 mol
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What is the empirical formula of a substance that contains 0.183 mol of carbon, 0.367 mol of hydrogen, and 0.183 mol of oxygen?
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CH2O
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Determine the molecular formula for the unknown if the molecular mass is 60.0 amu and the empirical formula is CH2O.
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C2H4O2
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The figure (Figure 1) shows the reaction of element A (lavender spheres) with element B (tan spheres). Write the balanced chemical equation for this reaction in terms of A and B.
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2A+3B2?2AB3
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Phosphoric acid reacts with magnesium hydroxide to produce magnesium phosphate and water via the following reaction: ?H3PO4+?Mg(OH)2??Mg3(PO4)2+?H2O Balance the equation, then enter the coefficients, in order, in the answer box. Enter four integers separated by commas.
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2,3,1,6
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You carefully weigh out 17.00 g of CaCO3 powder and add it to 68.85 g of HCl solution. You notice bubbles as a reaction takes place. You then weigh the resulting solution and find that it has a mass of 78.88 g . The relevant equation is CaCO3(s)+2HCl(aq)?H2O(l)+CO2(g)+CaCl2(aq) Assuming no other reactions take place, what mass of CO2 was produced in this reaction?
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6.97 g
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Based on the mole ratio you determined in Part C, what is the empirical formula of this compound? Express your answer as a chemical formula
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CH3
