How much work is done when a gas expands from an initial volume of 122 mL to a final volume of 175 mL against an external pressure of 858 mmHg?

Express your answer to two significant figures and include the appropriate units.

[tex]\[ W = \][/tex]
Value: ______
Units: ______



Answer :

Let's solve the problem step by step:

1. Convert Volumes from mL to L:

The initial volume is 122 mL, which can be converted to liters as follows:
[tex]\[ \text{Initial Volume} = 122 \, \text{mL} = 0.122 \, \text{L} \][/tex]

The final volume is 175 mL, which can be converted to liters as follows:
[tex]\[ \text{Final Volume} = 175 \, \text{mL} = 0.175 \, \text{L} \][/tex]

2. Convert Pressure from mmHg to atm:

The external pressure is 858 mmHg. To convert this to atmospheres:
[tex]\[ \text{Pressure} = \frac{858 \, \text{mmHg}}{760 \, \text{mmHg/atm}} = 1.129 \, \text{atm} \][/tex]

3. Determine the Change in Volume:

The change in volume ([tex]\( \Delta V \)[/tex]) is given by the final volume minus the initial volume:
[tex]\[ \Delta V = 0.175 \, \text{L} - 0.122 \, \text{L} = 0.053 \, \text{L} \][/tex]

4. Calculate the Work Done (W = -PΔV):

The work done by the gas is given by the formula [tex]\( W = -P \Delta V \)[/tex]:
[tex]\[ W = -1.129 \, \text{atm} \times 0.053 \, \text{L} = -0.0598 \, \text{L⋅atm} \][/tex]

5. Convert Work from L⋅atm to Joules:

To convert the work from L⋅atm to Joules, we use the conversion factor (1 L⋅atm = 101.325 J):
[tex]\[ W = -0.0598 \, \text{L⋅atm} \times 101.325 \, \text{J/L⋅atm} = -6.06 \, \text{J} \][/tex]

Final Answer:

The work done when the gas expands is:
[tex]\[ W = -6.06 \, \text{J} \][/tex]