Question

The value of δh° for the reaction below is 128.1 kJ: CH3OH (l) → CO (g) 2H2 (g) How many kJ of heat are consumed when 15.5 g of CH3OH (l) decomposes as shown in the equation?

A) 94.8 kJ
B) 128.1 kJ
C) 42.3 kJ
D) 71.4 kJ

Answer 1

To find the heat consumed when 15.5 g of CH3OH decomposes, we calculate the moles of methanol and multiply it by the given enthalpy change per mole which is 128.1 kJ.

Step-by-step explanation:

The student is asking how many kilojoules of heat are consumed when 15.5 g of CH3OH(l) decomposes, given the enthalpy change (ΔH°) of the reaction is 128.1 kJ. We can use the molar mass of methanol and the given enthalpy change to calculate this. First, we find the molar mass of CH3OH (32.04 g/mol) and then use it to convert 15.5 g of CH3OH to moles. We then multiply the number of moles by the enthalpy change per mole.

1. Calculate moles of CH3OH: Moles = 15.5 g / 32.04 g/mol.
2. Calculate heat consumed: Heat = Moles of CH3OH × 128.1 kJ/mol.

Following this calculation, the correct answer is B) 128.1 kJ of heat are consumed when 15.5 g of CH3OH(l) decomposes.