# My car has an internal volume of 2600 liters. Assume the pressure was initially 760 mm Hg. If the sun heats my car from a temperature of 20° C to a temperature of 55“ C, what will the pressure inside my car be?

##### 1 Answer

#### Explanation:

The idea here is that the volume of the car and the number of moles of gas you have in the car **remain unchanged**.

When volume and number of moles are kept constant, pressure and temperatue have a **direct relationship** - this is known as Gay Lussac's Law.

In simple terms, when the temperature of the gas *increases*, pressure **increases** as well. Likewise, when the temperature of the gas *decreases*, pressure **decreases** as well.

Mathematically, this is written as

#P_1/T_1 = P_2/T_2" "# , where

When plugging in your values into this equation, don't forget to convert the temperature from *degrees Celsius* to *Kelvin*.

So, rearrange and solve for

#P_2 = T_2/T_1 * P_1#

#P_2 = ((273.15 + 55)color(red)(cancel(color(black)("K"))))/((273.15 + 20)color(red)(cancel(color(black)("K")))) * "760 mmHg" = "850.74 mmHg"#

I'll leave the answer rounded to one sig fig, despite the fact that you only gave one sig fig for the initial temperature of the gas

#P_2 = color(green)("850 mmHg")#