Question

A 350 mL sample of air collected at 35°C has a pressure of 550 torr. What pressure will the air exert if it is allowed to expand to 425 mL at 57°C?

Answer 1

`485` `"torr"`

Explanation:

We can solve this equation using the combined gas law:

`(P_1V_1)/(T_1) = (P_2V_2)/(T_2)`

Remember, always use the absolute (Kelvin) temperature when working with gas equations.

The temperature conversions are

`T_1 = ""^"o""C" + 273 = 35^"o" + 273 = color(red)(308` `color(red)("K"`

`T_2 = 57^"o""C" + 273 = color(green)(330` `color(green)("K"`

Since we're trying to find the final pressure, let's rearrange this equation to solve for `P_2`:

`P_2 = (P_1V_1T_2)/(T_1V_2)`

Our known values:

`P_1 = 550` `"torr"`

`V_1 = 350` `"mL"`

`T_1 = color(red)(308` `color(red)("K"`

`V_2 = 425` "`mL"`

`T_2 = color(green)(330` `color(green)("K"`

Let's plug these into the equation to find the final pressure:

`P_2 = ((550"torr")(350cancel("mL"))(330cancel("K")))/((308cancel("K"))(425cancel("mL"))) = color(blue)(485` `color(blue)("torr"`

The final pressure after it is subjected to these changes is thus `color(blue)(485` `sfcolor(blue)("torr"`.