At , 50 g of iron reacts with hydrochloric acid to give ferrous chloride and evolved gas expands against a constant external pressure of 1 bar. The work done by the gas during this expansion is J.

Question

At , 50 g of iron reacts with hydrochloric acid to give ferrous chloride and evolved  gas expands against a constant external pressure of 1 bar. The work done by the gas during this expansion is  J.

[; Assume  is an ideal gas; Atomic mass of Fe = 55.85]

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Strategy:
 The work done by an expanding gas against a constant external pressure is calculated using the formula . For an ideal gas at constant temperature and pressure, this is equivalent to  (by substituting ).

Step 1: Write the balanced chemical equation

From the stoichiometry,  mole of  produces  mole of  gas.

Step 2: Calculate moles of  produced
Moles of .
Since ratio is , moles of .

Step 3: Calculate work done
The expansion occurs against constant atmospheric pressure ().
For evolved

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