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A gas expands from 3 dm^(3) to 5 dm^(3) ...

A gas expands from `3 dm^(3)` to `5 dm^(3)` against a constant pressure of 3 atm. The work done during expansion is used to heat 10 mol of water at a temperature of 290 K. Calculate final temperature of water. Specific heat of water `=4.184 J g^(-1)K^(-1)`

A

290.81 K

B

290.61 K

C

290.41 K

D

290.21 K

Text Solution

AI Generated Solution

The correct Answer is:
To solve the problem step by step, we will follow the outlined process to calculate the final temperature of the water after the gas expansion. ### Step 1: Calculate the Work Done by the Gas The work done (W) during the expansion of a gas at constant pressure can be calculated using the formula: \[ W = P \Delta V \] Where: - \( P \) = pressure in atm - \( \Delta V \) = change in volume in dm³ Given: - Initial volume \( V_1 = 3 \, \text{dm}^3 \) - Final volume \( V_2 = 5 \, \text{dm}^3 \) - Pressure \( P = 3 \, \text{atm} \) First, we calculate \( \Delta V \): \[ \Delta V = V_2 - V_1 = 5 \, \text{dm}^3 - 3 \, \text{dm}^3 = 2 \, \text{dm}^3 \] Now, substituting the values into the work formula: \[ W = 3 \, \text{atm} \times 2 \, \text{dm}^3 = 6 \, \text{atm} \cdot \text{dm}^3 \] To convert this to Joules, we use the conversion factor \( 1 \, \text{atm} \cdot \text{dm}^3 = 101.3 \, \text{J} \): \[ W = 6 \, \text{atm} \cdot \text{dm}^3 \times 101.3 \, \text{J/(atm} \cdot \text{dm}^3) = 607.8 \, \text{J} \] ### Step 2: Relate Work Done to Heat Transfer According to the first law of thermodynamics, the work done by the gas is equal to the heat absorbed by the water: \[ Q = W \] So, \( Q = 607.8 \, \text{J} \). ### Step 3: Calculate the Change in Temperature of Water The heat absorbed by the water can also be expressed using the specific heat capacity formula: \[ Q = m \cdot C \cdot \Delta T \] Where: - \( m \) = mass of water in grams - \( C \) = specific heat capacity of water - \( \Delta T \) = change in temperature in Kelvin Given: - Number of moles of water \( n = 10 \, \text{mol} \) - Molar mass of water \( = 18 \, \text{g/mol} \) - Specific heat of water \( C = 4.184 \, \text{J/(g} \cdot \text{K)} \) First, calculate the mass of water: \[ m = n \times \text{molar mass} = 10 \, \text{mol} \times 18 \, \text{g/mol} = 180 \, \text{g} \] Now, substituting the values into the heat equation: \[ 607.8 \, \text{J} = 180 \, \text{g} \times 4.184 \, \text{J/(g} \cdot \text{K)} \times \Delta T \] ### Step 4: Solve for \( \Delta T \) Rearranging the equation to find \( \Delta T \): \[ \Delta T = \frac{607.8 \, \text{J}}{180 \, \text{g} \times 4.184 \, \text{J/(g} \cdot \text{K)}} \] Calculating the denominator: \[ 180 \times 4.184 = 752.32 \, \text{J/K} \] Now substituting back: \[ \Delta T = \frac{607.8}{752.32} \approx 0.807 \, \text{K} \] ### Step 5: Calculate Final Temperature of Water The initial temperature of the water is given as \( T_1 = 290 \, \text{K} \). Therefore, the final temperature \( T_2 \) can be calculated as: \[ T_2 = T_1 + \Delta T = 290 \, \text{K} + 0.807 \, \text{K} \approx 290.807 \, \text{K} \] ### Final Answer The final temperature of the water is approximately: \[ T_2 \approx 290.81 \, \text{K} \] ---
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