# SAT II Chemistry : Solutions and States of Matter

## Example Questions

### Example Question #1 : Gas Laws

Suppose that an ideal gas at and 2.0 atm has a volume of 11.2 cubic meters. Which of the following expressions represents the volume of the gas, in cubic meters, if the temperature were increased by and the pressure decreased to 1.5 atm?      Explanation:

First of all, the unit degrees Celsius should be converted to Kelvins by adding 273. This means that the temperature increases from 273 K to 323 K.

Next, the combined gas law can be used. Plugging in the known values gives and solving for the volume gives Rearranging shows this is clearly equivalent to the correct answer, .

### Example Question #1 : Solutions And States Of Matter

How much faster is the rate of effusion of than the rate of effusion of ?      Explanation:

By Graham's Law, . The molar mass of is 2 g/mol and the molar mass of is 18 g/mol. Thus, ### Example Question #2 : Solutions And States Of Matter

30 mL of 1.0 M solution is diluted with water to a volume of 3 L. What is the new concentration of the solution?      Recall that Thus, the volume of the solution increased from 30 mL to 3000 mL, which is a factor of 100. Thus, the new concentration must be 100 times less than the original concentration, and . 