# Question #2a2bf

##### 2 Answers

Here's what I got.

#### Explanation:

The question is very vague, but I assume that you want to know what will happen to the pressure if you decrease temperature from

Since no mention of volume or number of moles of gas was made, you can assume that they are kept **constant**.

In this case, pressure and temperature have a **direct relationship** - this is known as Gay Lussac's Law.

When volume and number of moles of gas are kept constant, **increasing** temperature will cause the pressure to **increase** as well.

Likewise, **decreasing** temperature, like you have in your example, will cause the pressure to **decrease** as well.

Mathematically, Gay Lussac's Law can be written like this

#color(blue)(P_1/T_1 = P_2/T_2)" "# , where

Rearrange this equation and solve for **must be** expressed in Kelvin!

#P_2 = T_2/T_1 * P_1#

#P_2 = ( (273.15 + 85)color(red)(cancel(color(black)("K"))))/((273.15 + 100)color(red)(cancel(color(black)("K")))) * "760 torr" = color(green)("730 torr")#

Indeed, the pressure decreased sa a result of a decrease in temperature.

Check out this very cool video on Gay Lussac's Law!

I'm guessing you needed the final pressure. Answer is 729.45 Torr or 0.96 atm.

#### Explanation:

Gay Lussac's Law is expressed by the following formula:

This means, that at a constant mass and volume, the gas's temperature should increase when its pressure increases.

So substituting the values given in the formula, we have:

*373.15 K*

*358.15 K*

(760 torr) (358.15 K) =

Thus, **729.45 Torr**

or

**0.96 atm**