1.E: What Is Chemistry? (Exercises)
- Page ID
- 91993
Exercises (Basic Definitions)
1. Identify each as either matter or not matter.
- a book
- hate
- light
- a car
- a fried egg
2. Give an example of matter in each phase: solid, liquid, or gas.
3. Does each statement represent a physical property or a chemical property?
- Sulfur is yellow.
- Steel wool burns when ignited by a flame.
- A gallon of milk weighs over eight pounds.
4. Does each statement represent a physical property or a chemical property?
- A pile of leaves slowly rots in the backyard.
- In the presence of oxygen, hydrogen can interact to make water.
- Gold can be stretched into very thin wires.
5. Does each statement represent a physical change or a chemical change?
- Water boils and becomes steam.
- Food is converted into usable form by the digestive system.
- The alcohol in many thermometers freezes at about −40 degrees Fahrenheit.
6. Does each statement represent a physical change or a chemical change?
- Graphite, a form of elemental carbon, can be turned into diamond, another form of carbon, at very high temperatures and pressures.
- The house across the street has been painted a new color.
- The elements sodium and chlorine come together to make a new substance called sodium chloride.
7. Distinguish between an element and a compound. About how many of each are known?
8. What is the difference between a homogeneous mixture and a heterogeneous mixture?
9. Identify each as a heterogeneous mixture or a homogeneous mixture.
- Salt is mixed with pepper.
- Sugar is dissolved in water.
- Pasta is cooked in boiling water.
10. Identify each as a heterogeneous mixture or a homogeneous mixture.
- air
- dirt
- a television set
11. In Exercise 8, which choices are also solutions?
12. In Exercise 9, which choices are also solutions?
13. Why is iron considered a metal?
14. Why is oxygen considered a nonmetal?
15. Distinguish between a metal and a nonmetal.
16. What properties do semimetals have?
17. Elemental carbon is a black, dull-looking solid that conducts heat and electricity well. It is very brittle and cannot be made into thin sheets or long wires. Of these properties, how does carbon behave as a metal? How does carbon behave as a nonmetal?
18. Pure silicon is shiny and silvery but does not conduct electricity or heat well. Of these properties, how does silicon behave as a metal? How does silicon behave as a nonmetal?
Answers
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- matter
- not matter
- not matter
- matter
- matter
3. a. physical property
b. chemical property
c. physical property
5. a. physical change
b. chemical change
c. physical change
7. An element is a fundamental chemical part of a substance; there are about 115 known elements. A compound is a combination of elements that acts as a different substance; there are over 50 million known substances.
9. a. heterogeneous
b. homogeneous
c. heterogeneous
11. Choice b) is a solution.
13. Iron is a metal because it is solid, is shiny, and conducts electricity and heat well.
15. Metals are typically shiny, conduct electricity and heat well, and are malleable and ductile; nonmetals are a variety of colors and phases, are brittle in the solid phase, and do not conduct heat or electricity well.
17. Carbon behaves as a metal because it conducts heat and electricity well. It is a nonmetal because it is black and brittle and cannot be made into sheets or wires.
Exercises (Chemistry as a science)
- Describe the scientific method.
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What is the scientific definition of a hypothesis? Why is the phrase a hypothesis is just a guess an inadequate definition?
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Why do scientists need to perform experiments?
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What is the scientific definition of a theory? How is this word misused in general conversation?
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What is the scientific definition of a law? How does it differ from the everyday definition of a law?
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Name an example of a field that is not considered a science.
- Which of the following fields are studies of the natural universe?
- biophysics (a mix of biology and physics)
- art
- business
- Which of the following fields are studies of the natural universe?
- accounting
- geochemistry (a mix of geology and chemistry)
- astronomy (the study of stars and planets [but not the earth])
- Which of these statements are qualitative descriptions?
- Titanic was the largest passenger ship build at that time.
- The population of the United States is about 306,000,000 people.
- The peak of Mount Everest is 29,035 feet above sea level.
- Which of these statements are qualitative descriptions?
- A regular movie ticket in Cleveland costs $6.00.
- The weather in the Democratic Republic of the Congo is the wettest in all of Africa.
- The deepest part of the Pacific Ocean is the Mariana Trench.
- Of the statements in Exercise 9, which are quantitative?
- Of the statements in Exercise 10, which are quantitative?
Answers
- Simply stated, the scientific method includes three steps: (1) stating a hypothesis, (2) testing the hypothesis, and (3) refining the hypothesis.
- Scientists perform experiments to test their hypotheses because sometimes the nature of natural universe is not obvious.
- A scientific law is a specific statement that is thought to be never violated by the entire natural universe. Everyday laws are arbitrary limits that society puts on its members.
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- yes
- no
- no
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- qualitative
- not qualitative
- not qualitative
- Statements b and c are quantitative.