Think about the investigations you have completed throughout this unit. Why is it important to :

a. Compare your results to those of your classmates?

b. Compare your results to published data, when available?

c. Discuss your ideas with your classmates?

d. Reflect upon how your ideas have changed?

Considering the identity of the criteria pollutants and the sources of air pollutants in the United States where should air-qualit y monitoring devices be located? Explain .

Consider Investigating Matter B.8, Phase Changes.

a. What would be an appropriate beginning question for this investigation?

b. What are the variables of interest?

Collision theor y states that molecules can break bonds and form new substances when they collide with sufficient energy and suitable orientation . What types of evidence could support each of the following aspects of collision theory?

a. Formation of new substances.

b. Requirement for sufficient energy.

c. Requirement for suitable orientation

Heat is often described as "lost energy." For instance, automobile engines release about $75 \%$ of the energy from gasoline combustion as heat. Explain this idea of energy loss in terms of your understanding of heat.

What pattern would you expec t to find among pH readings taken of preci pit ation in the immedia te vicinity of an acid -rain producing smokestac k and at regular intervals downwind and upwind from the site? Sketch a graph of what you would expec t to find.

If air at $25^{\circ} \mathrm{C}$ has a density of $1.28 \mathrm{~g} / \mathrm{L}$ and your classroom has a volume of $2.0 \times 10^5 \mathrm{~L}$,

a. what mass of air is contained in your classroom?

b. assume that the room temperature is increased. How would that affect the total mass of air contained in the room,

i. if the room were tightly sealed?

ii. if the room were not sealed?

Consider the data you graphed in Developing Skills C.2.

a. List two scientific claims you could make based on the data or the graph.

b. For each claim, cite evidence for making that claim.

Why is the presence of ozone regar ded as a problem at ground leve l, whil e the absence of ozone is regarded as a prob lem in the stratosphere?

Write and balance the equation for formation of $\mathrm{SO}_3$ from $\mathrm{SO}_2$ and oxygen.

Use your own words to describe each of the following : How the relationships described in your answers.

What happens to the molecules in a sample of gas as it is heated?

Sketch the gas particles in

a. a balloon submerged in hot water .

b. a balloon submerged in ice water

What causes acid rain?