Question

WHOSE Good with Chemistry to figure this question out?

Calculate the work in joules if the external pressure is 825 torr.
Remeber 1 L atm = 101.3 J

Answer 1

Answer:

$\large \boxed{\text{220 J}}$

Explanation:

1. Convert the pressure to atmospheres

$p = \text{825 Torr} \times \dfrac{\text{1 atm}}{\text{760 Torr}} = \text{1.086 atm}$

2. Calculate the work done

$w = -p\Delta V = -p(V_{f} - V_{i}) = -\text{(1.086 atm)}(\text{2.0 L - 4.0 L})\\\\ = -\text{1.086 atm} \times \text{(-2.0 L)} = \text{2.17 L \cdot atm}$

3. Convert litre atmospheres to joules

$w = \text{2.17 L \cdot atm} \times \dfrac{\text{101.3 J}}{\text{1 L \cdot atm}} = \textbf{220 J}\\\\\text{The work done is \large \boxed{\textbf{220 J}} }$

Note that the volume is decreasing, so work is being done on the system.