# Question #dd7e8

##### 1 Answer

#### Explanation:

The trick here is to realize that when *volume* and *number of moles* of gas are **kept constant**, pressure and temperature have a **direct relationship** as described by **Gay Lussac's Law**.

In other words, when volume and number of moles are constant, **increasing** a gas' temperature will cause its pressure to *increase*, and **decreasing** the gas' temperature will cause its pressure to *decrease*.

In your case, the temperature of the gas increases from **increased** as well.

Mathematically, Gay Lussac's Law can be written as

#color(blue)(|bar(ul(color(white)(a/a)P_1/T_1 = P_2/T_2color(white)(a/a)|)))" "# , where

Rearrange the equation to solve for

#P_1/T_1 = P_2/T_2 implies P_2 = T_2/T_1 * P_1#

Plug in your values to find

#P_2 = (684 color(red)(cancel(color(black)("K"))))/(428color(red)(cancel(color(black)("K")))) * "86 atm" = color(green)(|bar(ul(color(white)(a/a)color(black)("140 atm")color(white)(a/a)|)))#

The answer is rounded to two **sig figs**, the number of sig figs you have for the initial pressure of the gas.