Chemistry 1020

Why is independent verification of scientific results critically important to the scientific method?
It helps insures that the results and observations obtained are unbiased by a predisposition to support a particular hypothesis
Chemistry is the study of ________.
Matter
Which of the following is an example of a physical change?
Water boiling and being converted into steam
A scientific hypothesis is a(n) ________.
Testable assumption used to explain an observation
The “Clever Hans” effect is very important to consider in any experimental design because:
The trainer was unaware that he was prompting a particular response
The following statement is an examples of which step in the scientific process?
“We will test the assumption that consumption of fish or long-chain omega-3 polyunsaturated fatty acids (n-3 LC-PUFAs) provides primary protection against cardiovascular disease.”
A hypothesis
Which of the following is an example of a chemical change?
Chemistry is a science, and as such:
All of the above: it is dynamic, objective, complex
If the results of an experiment turn out differently from your expectations, then:
You need to do the experiment over until you get the expected result
The term “Pathological Science” was coined by Iving Langmuir to mean:
The science of things that are not so
In 1961, Process Charles C. Price announced the discovery of a new class of compounds known as thiabenzenes. Over the next 11 years he and his coworkers published 9 scientific papers on this subject. The fact that these papers where in error, and the thiabenzenes did not have any of the properties that Price and his coworkers attributed to them, illustrates what important point about doing scientific research?
The power of observer bias and group thinking is very powerful, and it can cause even very competent researchers to make significant errors in scientific interpretation and judgement
Classify the following changes as physical or chemical. Wood burns to ashes; water begins to boil; grass grows a rock is crushed to powder.
Chemical, physical, chemical, physical
Which of the following statements would best describe an independent verification of an experimental result?
The result is repeated in several laboratories that are unconnected in any way to the initial experimental finding
If you have a control group for your experiment, which of the following is true:
If more than one difference exists between the control and the test then this enables the scientist to more easily analyze the experimental data
In Nicholas Turro’s paper, “Toward a General Theory of Pathological Science” he cautions that a researcher should be viewed skeptically if they:
Advocate their views to the public before there have been critical efforts by the scientific community to either prove or disprove their initial findings
Each circle represents an atom. Which of the following boxes contains an element? A compound A mixture?
Element: A, C; compound: A, B, C; Mixture: A, B
What are the steps in the scientific method in their paper order?
Observation, question, hypothesis formulation, predictions, testing
A scientific attitude is typified by
all: belief, love, desire, objective
Scientists have noted a decline in fungi species dating back to the early 1900’s. Annual crops of edible mushrooms in France and Germany have declined since 1950. One hypothesis to explain this decline in overharvesting. Global warming and increased air pollution are other factors that could contribute to the observed decline. Which of the following observations would exclude overharvesting as the cause of the decline?
Fungal population increase in tropical regions
Which of the following best describes a theory?
An idea that has been extensively tested in a single laboratory
Is chemistry the study of the submicroscopic, the microscopic, or the macroscopic, or all three?
All of the above because everything is made of atoms and molecules
Is the following transformation representative of a physical change or a chemical change?
Chemical change because the atoms are connected differently
A hypothesis is a testable explanation for an observation. Which of the following statement is most true about the testing of a hypothesis?
unanswer
The following statement is an example of which step in the scientific process?
Observing a natural phenomenon
Distinguish between a scientific hypothesis and a law.
A scientific hypothesis is a testable assumption that relates to a specific observation. A law is developed from a large number of consistent observations and represents a generalized, concise statement of this data
The following image describes what time of change: 2 dark molecules, 2 gray molecules form into one gray molecule attached to one small molecule:
A chemical change
The following image describes which type of change? All circle on the bottom -> all circle spread out: all same size
A physical change
For each of the follow, determine whether the change described in physical or chemical or both: boiling water, popping popcorn, fog forming on the inside of your car windshield, nail rusting, salt crystals forming on the evaporation of brine (a solution of salt dissolved in water)
Physical both Physical Chemical Physical
1) What is the main difference between the deductive or Aristotelian logic used by the Greeks and the type of inductive logic that was introduced by Boyle to investigate the nature of matter.
Inductive conclusion must always be held to be true and can not change; deductive conclusions can change based on new observations. 2) Match the following chemists with their major discoveries. You may use the same chemist more than once to correctly answer this question.
1) Discovered the charge/mass ratio of the electron
2) Proposed the modern structure of the atom
3) Determine the charge on the electron
4) Proposed the “Plum Pudding” model for the atom
5) Directed alpha particles at a gold foil to gain an understanding of the structure of the atom
a) Mililikan
b) Thomson
c) Rutherford
d) Crookes
e) Geissler
1) b; 2) c; 3) a; 4) b; 5
Since atoms are mostly empty space, why don’t objects pass through one another?
The electrons of one substance repel the electrons of an adjacent substance when they get close.
Naturally-occurring elemental chlorine consists of 75.77% chlorine-35 (mass 34.97 amu) and 24.23% chlorine-37 (mass 36.97 amu). Chlorine-37 has 17 protons and 20 neutrons. Why is the observed mass of chlorine-37 not equal to the sum of the mass of its protons and neutrons (i.e., 37.30 amu)?
Some mass has been converted to energy to bind the nucleus together
Which of the following volumes of N2 react with nine (9) liters of H2 to form six (6) liters of NH3
3 Liters
A liter of chlorine gas is found to have a mass of 3.165 grams. A liter of hydrogen gas under the same conditions is found to have a mass of 0.0900 grams. How much heavier are chlorine atoms compared to hydrogen atoms?
A liter of hydrogen gas contains 35.2 times as many particles as a liter of chlorine gas. Therefore, individual chlorine atoms and hydrogen atoms have exactly the same mass.
Which of the following scientists would be considered the father of the modern periodic table?
Mendeleev
The following diagram depicts the reaction between gaseous oxygen, O2, and gaseous hydrogen, H2, to form water vapor, H2O. What molecules and how many of them should be drawn in the empty box? How many grams of water are formed under these conditions? How many grams of which chemical remain unreacted (assuming that the pictures below are proportional to the combining mass ratio)?
five H2 molecules in empty box; 9 grams of H2O + 0.5 grams of H2
If a neutral element has the following chemical notation, how many electrons does it have? Iodine-127
53
Which of the following elements is not a diatomic molecule in its natural state?
phosphorus
A large truck fuel tank holds 84 kg of diesel fuel. When the diesel fuel burns, 336 kg of oxygen are consumed and carbon dioxide and water are produced. What is the total combined mass of carbon dioxide and water that is produced?
4.2 x 10^2 kg
According to the Law of Definite Proportion, why is only 27 grams of water formed when 50 grams of oxygen reacts with 3 gram of hydrogen?
because oxygen and hydrogen only react in an 8:1 mass ratio
If you remove a proton and a neutron from a phosphorous-31 atom (P-31), what is formed?
Si-29
Match each of the statements below with the chemical species that matches the description. You may use the same species more than once to correct answer this question.

1) Same number of protons, neutrons, and electrons
2) Same number of electrons and neutrons; different number of protons
3) Isotopic mass of 27
4) Three (3) more electrons than protons
5) Same number of electrons as Ne-20

a) 23Na+
b) Aluminum-27
c)31P-3
d)Sulfur-32
e)18O2-

1) d; 2) e; 3) b; 4) c; 5) a
1) Law of Mass Conservation
2) Law of Definite Proportion
3) Atomic Theory of Matter
4) Periodic Table
5) Discoverer of Oxygen

a) Dalton
b) Lavoisier
c) Avogadro
d) Proust
e) Mendeleev

1) b; 2) d; 3) a; 4) e; 5) b
The mass ratio of lead sulfide (PbS) is 86.6 g Pb to 13.4 g S. How much sulfur remains unreacted when you react 86.6 g of Pb with 100 g of S to form PbS?
86.6 g of sulfur
In the Rutherford atomic model, mass is concentrated in the nucleus of the atom. To demonstrate how massive nuclear material is, calculate the density (in kg/m3) of the carbon atom’s nucleus assuming that the shape of the nucleus is a sphere. The radius of the carbon atoms nucleus is 2.18×10-15 m and the mass of the carbon atom’s nucleus is 1.992×10-26 kg (12 amu).
Note: the formula for the volume of a sphere is (4/3)π(radius)3 and the formula for density is: density = mass/volume
4.59 x 10^17 kg/m^3
Which statement or statements are true
The Cu2+ ion contains 29 protons and 27 electrons.
Which of the following is the best definition of an isotope?
element with the same number of protons but a different number of neutrons
Which of the following statements best describes the Law of Conservation of Mass.
In a chemical process, the mass of all the products will be the same as the mass of all the reactants.
If 44 kg of propane (C3H8) is burned in air to produce 204 kg of carbon dioxide and water vapor, how much oxygen (from the air) was consumed in this process? C3H8 + 5O2 → 3CO2 + 4H2O
160 kg
Lavoisier heated a piece of tin on a floating block of wood covered by a glass jar. As the tin decomposed, the water level inside the jar rose. How did Lavoisier explain this result?
Some component of the air was being absorbed by the tin
Which of the following carbon to oxygen mass ratios is the same as the mass ratio found in carbon dioxide (3 g carbon for every 8 g oxygen)?
12 lb carbon for every 32 lb oxygen
The mass ratio of lead sulfide (PbS) is 86.6 g Pb to 13.4 g S. How much lead sulfide is formed when you react 86.6 g of Pb with 46.6 g of S to form PbS?
100 g of PbS
What prompted early scientists to propose that the ray of the cathode ray tube was actually a negatively charged particle?
The ray was attracted to a positively charged electric plate
The following diagrams depict the reaction between gaseous chlorine, Cl2 and gaseous hydrogen, H2, to form gaseous hydrogen chloride, HCl. What should be drawn in the empty box? If 71 grams of chlorine are reacted with 1 gram of hydrogen how many grams of products are formed (assuming that the pictures below are proportional to the combining mass ratio)?
five Cl2 molecules in empty box; 36.5 grams of HCl + 35.5 grams of Cl2
Which of the following statement(s) is/are inconsistent with Dalton’s atomic theory as it was originally stated?
blank
What does the following element description actually mean? copper-64
copper with a mass number of 64
chronological order: discoveries
1. Elements are made of atoms.
2. Chemicals react in definite whole-number ratios.
3. Discovery of the electron
4. Matter is composed of elements
5. The Periodic Table of the Elements
4, 2, 1, 5, 3
An element has two principal isotopes. Isotope 1 has a mass of 34.9689 amu and a relative abundance of 76.56%, and isotope 2 has a mass of 36.9659 amu and a relative abundance of 24.24%. Identify the element and its average atomic mass?
chlorine (35.453)
Which statement or statements are true?
a) The Ti2+ ion contains 22 protons and 24 electrons.
b) The I- ion contains 53 protons and 54 electrons.
c) The Mg2+ ion contains 14 protons and 12 electrons.
d) The O2- ion contains 8 protons and 10 electrons
The I- ion contains 53 protons and 54 electrons
The O2- ion contains 8 protons and 10 electrons
You place a piece of sodium metal that weighs exactly 1 gram into a container and seal it. The weight of the container and its contents is exactly 10 g. You allow it to sit for a week and then reweigh the container. After one week the weight of the container and its contents now weigh 12 g. The mass of the sample inside is now 3.0 g. What is the best explanation for this observation?
The container had a leak because mass of the sodium plus sealed container increased
What does the following element description actually mean?
28
Si
34
a silicon atom with 14 protons and 14 neutrons
What was the main advantage of arranging the periodic table so that the elements were grouped by chemical properties?
It predicted the properties of undiscovered elements and helped lead to discoveries about the electron and other subatomic particles.
The mass number shown in the periodic table is _______.
average atomic mass of all of the naturally-occurring isotopes
the average sum of the protons and the neutrons for all the naturally-occurring isotopes
What observation made during Rutherford’s now famous gold-foil experiment led to the model for the atom with a small, but massive nucleus surrounded by electrons which occupy the bulk of the atomic volume.
because a beam of positively charged particles (alpha particles) were partially reflected by a thin gold foil
The boron atom contains 5 protons, 6 neutrons, and 5 electrons. The radius of the boron nucleus is approximately 2.052 femtometer (2.052×10-15 meter), and radius of the boron atom is approximately 87 picometers (87×10-12 meter). Assuming that the shape of both the boron atom and its nucleus are spherical, how many times larger is the boron atom compared to its nucleus?
Note: the formula for the volume of a sphere is (4/3)π(radius)3
7.6 x 10^13 times
Which of the following statement or statements are consistent with the modern model of the atom:
Avogadro hypothesized that hydrogen and oxygen were both diatomic molecules
If the mass ratio of lead sulfide (PbS) is 86.6 g of lead (Pb) to 13.4 g of sulfur (S), how much sulfur is needed to completely react 45 g of lead to form lead sulfide?
6.9 g of sulfur