Chapter 1 – Review
1.1 Chemistry in Context
- Explain how you could experimentally determine whether the outside temperature is higher or lower than 0 °C (32 °F) without using a thermometer. Check Answer: [1]
- Identify each of the following statements as being most similar to a hypothesis, a law, or a theory. Explain your reasoning.
- Falling barometric pressure precedes the onset of bad weather.
- All life on earth has evolved from a common, primitive organism through the process of natural selection.
- My truck’s gas mileage has dropped significantly, probably because it’s due for a tune-up.
- Identify each of the following statements as being most similar to a hypothesis, a law, or a theory. Explain your reasoning.
- The pressure of a sample of gas is directly proportional to the temperature of the gas.
- Matter consists of tiny particles that can combine in specific ratios to form substances with specific properties.
- At a higher temperature, solids (such as salt or sugar) will dissolve better in water.
Check Answer: [2]
- Identify each of the following bolded items (also preceded by *) as a part of either the macroscopic domain, the microscopic domain, or the symbolic domain of chemistry. For any in the symbolic domain, indicate whether they are symbols for a macroscopic or a microscopic feature.
- The mass of a *lead pipe is 14 lb.
- The mass of a certain *chlorine atom is 35 amu.
- A bottle with a label that reads *Al contains aluminum metal.
- *Al is the symbol for an aluminum atom.
- Identify each of the following bolded items (also preceded by *) as a part of either the macroscopic domain, the microscopic domain, or the symbolic domain of chemistry. For those in the symbolic domain, indicate whether they are symbols for a macroscopic or a microscopic feature.
- A certain molecule contains one *H atom and one Cl atom.
- *Copper wire has a density of about 8 g/cm3.
- The bottle contains 15 grams of *Ni powder.
- A *sulfur molecule is composed of eight sulfur atoms.
Check Answer: [3]
- According to one theory, the pressure of a gas increases as its volume decreases because the molecules in the gas have to move a shorter distance to hit the walls of the container. Does this theory follow a macroscopic or microscopic description of chemical behaviour? Explain your answer.
- The amount of heat required to melt 2 lbs of ice is twice the amount of heat required to melt 1 lb of ice. Is this observation a macroscopic or microscopic description of chemical behaviour? Explain your answer. Check Answer: [4]
1.2 Phases and Classification of Matter
- Why do we use an object’s mass, rather than its weight, to indicate the amount of matter it contains?
- What properties distinguish solids from liquids? Liquids from gases? Solids from gases? Check Answer: [5]
- How does a heterogeneous mixture differ from a homogeneous mixture? How are they similar?
- How does a homogeneous mixture differ from a pure substance? How are they similar? Check Answer: [6]
- How does an element differ from a compound? How are they similar?
- How do molecules of elements and molecules of compounds differ? In what ways are they similar? Check Answer: [7]
- How does an atom differ from a molecule? In what ways are they similar?
- Many of the items you purchase are mixtures of pure compounds. Select three of these commercial products and prepare a list of the ingredients that are pure compounds. Check Answer: [8]
- Classify each of the following as an element, a compound, or a mixture:
- copper
- water
- nitrogen
- sulfur
- air
- sucrose
- a substance composed of molecules each of which contains two iodine atoms
- gasoline
- Classify each of the following as an element, a compound, or a mixture:
- iron
- oxygen
- mercury oxide
- pancake syrup
- carbon dioxide
- a substance composed of molecules each of which contains one hydrogen atom and one chlorine atom
- baking soda
- baking powder
Check Answer: [9]
- A sulfur atom and a sulfur molecule are not identical. What is the difference?
- How are the molecules in oxygen gas, the molecules in hydrogen gas, and water molecules similar? How do they differ? Check Answer: [10]
- We refer to astronauts in space as weightless, but not without mass. Why?
- As we drive an automobile, we don’t think about the chemicals consumed and produced. Prepare a list of the principal chemicals consumed and produced during the operation of an automobile. Check Answer: [11]
- Matter is everywhere around us. Make a list by name of fifteen different kinds of matter that you encounter every day. Your list should include (and label at least one example of each) the following: a solid, a liquid, a gas, an element, a compound, a homogenous mixture, a heterogeneous mixture, and a pure substance.
- When elemental iron corrodes it combines with oxygen in the air to ultimately form red brown iron(III) oxide which we call rust.
- If a shiny iron nail with an initial mass of 23.2 g is weighed after being coated in a layer of rust, would you expect the mass to have increased, decreased, or remained the same? Explain.
- If the mass of the iron nail increases to 24.1 g, what mass of oxygen combined with the iron? Check Answer: [12]
- As stated in the text, convincing examples that demonstrate the law of conservation of matter outside of the laboratory are few and far between. Indicate whether the mass would increase, decrease, or stay the same for the following scenarios where chemical reactions take place:
- Exactly one pound of bread dough is placed in a baking tin. The dough is cooked in an oven at 350 °F releasing a wonderful aroma of freshly baked bread during the cooking process. Is the mass of the baked loaf less than, greater than, or the same as the one pound of original dough? Explain.
- When magnesium burns in air a white flaky ash of magnesium oxide is produced. Is the mass of magnesium oxide less than, greater than, or the same as the original piece of magnesium? Explain.
- Antoine Lavoisier, the French scientist credited with first stating the law of conservation of matter, heated a mixture of tin and air in a sealed flask to produce tin oxide. Did the mass of the sealed flask and contents decrease, increase, or remain the same after the heating?
- Yeast converts glucose to ethanol and carbon dioxide during anaerobic fermentation as depicted in the simple chemical equation here:
[latex]\text{glucose} \rightarrow \text{ethanol + carbon dioxide}[/latex]
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If 200.0 g of glucose is fully converted, what will be the total mass of ethanol and carbon dioxide produced?
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If the fermentation is carried out in an open container, would you expect the mass of the container and contents after fermentation to be less than, greater than, or the same as the mass of the container and contents before fermentation? Explain.
- If 97.7 g of carbon dioxide is produced, what mass of ethanol is produced?
Check Answer: [13]
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Attributions & References
Except where otherwise noted, this page is adapted by JR van Haarlem from “1.1 Chemistry in Context” and “1.2 Phases and Classification of Matter” In General Chemistry 1 & 2 by Rice University, a derivative of Chemistry (Open Stax) by Paul Flowers, Klaus Theopold, Richard Langley & William R. Robinson and is licensed under CC BY 4.0. Access for free at Chemistry (OpenStax) / Summary and exercises from the two sections combined into review for our version.
- Place a glass of water outside. It will freeze if the temperature is below 0 °C. ↵
- (a) law (states a consistently observed phenomenon, can be used for prediction); (b) theory (a widely accepted explanation of the behaviour of matter); (c) hypothesis (a tentative explanation, can be investigated by experimentation) ↵
- (a) symbolic, microscopic; (b) macroscopic; (c) symbolic, macroscopic; (d) microscopic ↵
- Macroscopic. The heat required is determined from macroscopic properties. ↵
- Liquids can change their shape (flow); solids can’t. Gases can undergo large volume changes as pressure changes; liquids do not. Gases flow and change volume; solids do not. ↵
- The mixture can have a variety of compositions; a pure substance has a definite composition. Both have the same composition from point to point. ↵
- Molecules of elements contain only one type of atom; molecules of compounds contain two or more types of atoms. They are similar in that both are comprised of two or more atoms chemically bonded together. ↵
- Answers will vary. Sample answer: Gatorade contains water, sugar, dextrose, citric acid, salt, sodium chloride, monopotassium phosphate, and sucrose acetate isobutyrate. ↵
- (a) element; (b) element; (c) compound; (d) mixture, (e) compound; (f) compound; (g) compound; (h) mixture ↵
- In each case, a molecule consists of two or more combined atoms. They differ in that the types of atoms change from one substance to the next. ↵
- Gasoline (a mixture of compounds), oxygen, and to a lesser extent, nitrogen are consumed. Carbon dioxide and water are the principal products. Carbon monoxide and nitrogen oxides are produced in lesser amounts. ↵
- (a) Increased as it would have combined with oxygen in the air thus increasing the amount of matter and therefore the mass. (b) 0.9 g ↵
- (a) 200.0 g; (b) The mass of the container and contents would decrease as carbon dioxide is a gaseous product and would leave the container. (c) 102.3 g ↵