A solution of 6.3 g of haemoglobin (molar mass = 64,000 g/mol) in 25 ml of solution shows a temperat — Thermodynamics and Thermochemistry Chemistry Question
Question
A solution of 6.3 g of haemoglobin (molar mass = 64,000 g/mol) in 25 ml of solution shows a temperature rise of $0.03^\circ\text{C}$ for complete oxygenation. Each mole of haemoglobin binds 4 moles of oxygen. If the heat capacity of the solution is 4.2 J/K-ml, the amount of heat released per mole of oxygen bound (in kJ) is
Answer: 8
💡 Solution & Explanation
Moles of haemoglobin = $6.3 / 64000 = 9.84 \times 10^{-5}\text{ mol}$. Moles of $\text{O}_2$ bound = $4 \times 9.84 \times 10^{-5} = 3.9375 \times 10^{-4}\text{ mol}$. Heat capacity of 25 ml solution = $25 \times 4.2 = 105\text{ J/K}$. Total heat released = $105 \times 0.03 = 3.15\text{ J}$. Heat per mole of $\text{O}_2$ = $3.15 / (3.9375 \times 10^{-4}) = 8000\text{ J} = 8\text{ kJ}$.
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