Chemistry Chapter 2A
What is a physical change? Give three examples of physical changes.
A physical change results only in a rearrangement of the particles of matter, not in their composition. Examples include crushing, dissolving, hammering into a thin sheet, or changing state. (§2.3)
Differentiate between physical and chemical properties of matter. Give two examples of each property.
A physical property of matter can be determined or observed without altering the chemical composition of the matter. Examples include color, hardness, electrical conductivity and malleability. A chemical property can be determined only through a change to the material that permanently alters its composition. Examples include combustion in the presence of oxygen and decomposition in the presence of an electrical current.
Explain the difference between heterogeneous and homogeneous mixtures.
Heterogeneous mixtures consist of two or more materials segregated into distinct pieces, regions, or phases (e.g. granite). A homogeneous mixture is a physical combination of two or more pure substances where the individual particles of the substances are uniformly distributed throughout the mixture (e.g. salt water). (§2.5)
How is shot peening an example of using technology to exercise dominion and to love your neighbor as yourself
Loss of life and expense as well as exploitation of the natural resource God has given us can all be avoided with a process like shot or laser peening. (§§2.3-2.4)
What is matter and where did it come from?
Matter is anything that occupies space and has mass. All matter was created during the events of Creation Week when it was spoken into existence by God.
What property of metal does shot peening use?
Shot peening uses the malleability of metal to increase its strength. (§§2.3-2.4)
Describe the two kinds of pure substances. How do these differ from mixtures?
The particles in pure substances consist of all one kind of atom (a single element) or those that make up only one compound. Pure substances differ from mixtures in that mixtures are combinations of two or more substances that are not chemically combined.
What are the two main classes of matter and what characteristics differentiate them?
The two main classes of matter are pure substances and mixtures. A pure substance consists of only one kid of matter that is chemically combined (an element or a compound). A mixture is a physical combination of two or more substances. (§2.5)
What kind of change does shot peening cause in a sheet of metal? Why is it that type of change?
This is an example of a physical change because the substance is not changed. (§§2.3-2.4)