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Chemistry Answers

Chapter 1

4. Basic research describes the desire to increase knowledge like the how and why a reaction occurred or the properties of a specific substance. An example is the serendipitous discovery of Teflon by Roy Plunkett; through basic research, the properties, structure, and composition were determined. Applied research refers to solving a problem that requires attention. This includes inventing new refrigerants that are more environmentally safe. Technological development involves the production and use of products that improve the quality of life. An example is the emergence of computers.

5. a) Mass is a measure of the amount of matter.

b) Volume is the amount of 3D space an object occupies.

6. A pure compound is composed of the atoms of two or more elements chemically bonded and has the same properties as well as compositions. A mixture is a blend of two or more kinds of matter, each of which retains its own identity and properties.

7. a) A property is a characteristic that helps classify uniqueness

b) Properties are useful in classification because they distinguish certain aspects that    can be grouped together with similar other aspects. They reveal identities of unknown substances.

8. Extensive properties depend on the amount of matter that is present while intensive properties do NOT depend on the amount of matter present. For example, intensive properties are the same for a given substance regardless of the amount present.

9. a) A physical property is a trait that can be observed or measured without changing the

identity of the substance.

b) Two examples include melting and boiling points.

10. a) A chemical property relates to a substance’s ability to undergo changes that

transform it into different substances.

b) Two examples include charcoal burning and iron rusting.

11. A physical change doesn’t involve a change in the identity of a substance. A chemical change is when one or more substances are converted into different substances.

12. a) A solid differs from a liquid in that it has a definite shape.

b) A liquid differs from a gas in that it has definite volume.

c) A liquid is similar to gas because it has indefinite shape.

d) Plasma is a high-temperature physical state of matter in which atoms lose their

electrons.

13. A change in state is a physical change of a substance from one state (solid, liquid, or  gas) to another.

17. Potassium and water comprises the reactants, and potassium hydroxide and hydrogen are the products.

19. a) Sawing a piece of wood in half is a physical change since it doesn’t change the

identity of wood.

b) Milk turning sour is a chemical change since it changes into a different substance.

c) Butter solidifying is a physical change since it doesn’t change its identity.

22. a) applied research

b) basic research

c) technological development

24. a) I can conclude that it’s most likely a heterogeneous mixture.

b) I can conclude that it’s a pure substance because every sample has exactly the

same composition.

 

Chapter 2

1. Quantitative information involves numerical data while qualitative information involves descriptive data.

2. A hypothesis is a testable statement.

3. a) A model in science is more than a physical object, and it is often an explanation of

how phenomena occur and how data or events are related.

b) A model needs to explain many phenomena in order to be considered part of a

theory.

4. It is important for a measurement system to have an international standard because then people all around the world can utilize a known system in order to prevent confusion. Also, there are organizations that monitor the defining process.

5. A quantity is something that has size, magnitude, or amount. Units of measurement represent quantities. For example, the quantity of a teaspoon is volume. The unit is the teaspoon, but the volume is the quantity. Another example is the balance to measure mass. The choice of unit depends on quantity being measured.

6. Meter-length; kilogram-mass; second-time; Kelvin-temperature; mole-amount of substance; ampere-electric current; candela-luminous intensity.

7. a) kilo-1000

b) centi- 1/100

c) mega-1,000,000

d) micro- 1/ 1,000,000

e) milli- 1/1000

8. a) meter

b) centimeter

c) kilometer

d) nanometer

9. a) kilogram

b) decigram

c) gram

10. The second is not defined by the length of day because there are too many seconds in a day. It would be illogical to use such a small unit.

11. a) A derived units are combinations of SI base units.

b) square meter (m^2)

12. a) cubic meter (m^3) and molar volume (m^3/mol)

b) Liter (L) and milliliter (mL). A liter is equivalent to 1000cm^3 and the mL is equal

to the cubic centimeter.

27. 7.4725 m^3

28. 1.55 g/mL

29. 370.272 g

30. .54733 mL

48. 1409725 m^3

 

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