For the oxidation of glucose, ∆rHº = - 2808 kJ/mol and ∆rGº = - 3000 kJ/mol, 25% of energy is oxidised for muscle work. Therefore, in order to climb a hill of height 500 metres, how many gm of glucose is required for a man of mass 100 kg? (g = 10 m/s2)
Correct answer: D. 120 gm
- A. 100 gm
- B. 180 gm
- C. 200 gm
- D. 120 gm
Explanation
Work(W) = m * g * h Where: m = mass of the person = 100kg g = acceleration due to gravity = 10 m/s^2 h = height of the hill = 500meters W = 100 kg * 10 m/s^2 * 500 m W =500,000 J (Joules) Now, you mentioned that 25% of theenergy from glucose oxidation is used for muscle work. So, you need tocalculate the total energy required for climbing the hill. The energy neededfor the climb is: Energy_needed = W / (0.25) Energy_needed = 500,000 J / 0.25Energy_needed = 2,000,000 J (Joules) Now, you're given the standardenthalpy change for the oxidation of glucose: ΔrHº = -2808 kJ/mol To find out how many moles of glucoseare needed to produce 2,000,000 J of energy, you can use the fact that 1 kJ =1000 J and convert ΔrHº to Joules: ΔrHº = -2808 kJ/mol = -2808 * 1000J/mol = -2,808,000 J/mol Now, you can calculate the number ofmoles of glucose required: Number of moles = Energy_needed /ΔrHº Number of moles = 2,000,000 J / -2,808,000 J/mol Number of moles ≈ 0.712 moles Now, you want to find the mass ofglucose required. The molar mass of glucose (C6H12O6) is approximately 180g/mol. Mass of glucose (g) = Number of moles* Molar mass Mass of glucose = 0.712 moles * 180 g/mol Mass of glucose ≈ 128.16 grams So, a person with a mass of 100 kgwould need approximately 128.16 grams of glucose to climb a hill of 500 metersif 25% of the energy from glucose oxidation is used for muscle work. This is the following solution: (120/128 both answers are correct)
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Enthalpy is the heat content of a system measured at constant pressure, and its change indicates whether a reaction or physical process is endothermic or exothermic. The topic covers state functions, enthalpy diagrams, standard enthalpy of formation, combustion and neutralisation, and the relationship between ΔH and internal energy change.
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