Math Problem Statement

A gas is compressed at a constant pressure of 0.208 atm from 7.87 L to 5.54 L. In the process, 638 J of energy leaves the gas by heat. What is the work done on the gas? Remember: 1 atm = 1.013 × 105 Pa. Answer in units of J.

Solution

To determine the work done on the gas during compression, we use the formula for work done in a constant pressure process:

W=PΔVW = -P \Delta V

Where:

  • WW = work done on the gas (J)
  • PP = pressure (Pa)
  • ΔV\Delta V = change in volume (VfViV_f - V_i) (m³)

Step 1: Convert pressure from atm to Pa

P=0.208atm×1.013×105PaatmP = 0.208 \, \text{atm} \times 1.013 \times 10^5 \, \frac{\text{Pa}}{\text{atm}} P=2.107×104PaP = 2.107 \times 10^4 \, \text{Pa}

Step 2: Convert volume from liters to cubic meters

1L=1×103m31 \, \text{L} = 1 \times 10^{-3} \, \text{m}^3 Vi=7.87L=7.87×103m3V_i = 7.87 \, \text{L} = 7.87 \times 10^{-3} \, \text{m}^3 Vf=5.54L=5.54×103m3V_f = 5.54 \, \text{L} = 5.54 \times 10^{-3} \, \text{m}^3

Step 3: Calculate the change in volume

ΔV=VfVi=5.54×1037.87×103=2.33×103m3\Delta V = V_f - V_i = 5.54 \times 10^{-3} - 7.87 \times 10^{-3} = -2.33 \times 10^{-3} \, \text{m}^3

Step 4: Calculate the work done

W=PΔVW = -P \Delta V W=(2.107×104)×(2.33×103)W = - (2.107 \times 10^4) \times (-2.33 \times 10^{-3}) W=49.1JW = 49.1 \, \text{J}

Final Answer:

The work done on the gas is: 49.1J\boxed{49.1 \, \text{J}}

Would you like further explanation or assistance?
Here are 5 related questions to consider:

  1. What is the significance of the negative sign in work calculations?
  2. How would the work change if the gas were expanding instead of compressing?
  3. Can you calculate the total energy change of the system?
  4. What happens to the heat energy in this process?
  5. How is the First Law of Thermodynamics applied in this scenario?

Tip: Always check unit consistency when working with physical equations to avoid calculation errors.

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Math Problem Analysis

Mathematical Concepts

Thermodynamics
Work and Energy
Pressure-Volume Work

Formulas

W = -P ΔV

Theorems

First Law of Thermodynamics

Suitable Grade Level

Grades 10-12