Answer:
The ΔH of this combustion reaction is -502 kJ/mol
Explanation:
Step 1: Data given
Mass of water = 500.0 grams
Mass of fuel = 5.00 grams
Initial temperature = 20.0 °C
Final temperature = 50.0°C
The specific heat of water is 4.184 J/g°C
Molecular weight of the fuel is 40.0 g/mol
Step 2: Calculate the heat transfer
q = m*c* ΔT
⇒ with m = the mass of water = 500 grams
⇒ with c = the specific heat of water = 4.184 J/g°C
⇒ with ΔT = the change in temperature = T2 - T1 = 50.0°C- 20.0°C = 30.0°C
q = 500 * 4.184 * 30
q= 62760 J
Step 3: Calculate moles
moles = mass / molar mass
Moles = 5 grams / 40 g/mol
moles = 0.125 moles
Step 4: Calculate ΔH of this combustion reaction
ΔH = 62760 / 0.125 mol
ΔH = 502080 J/mol = 502 kJ /mol ( negative because it's an exothermic reaction)
ΔH = -502 kJ/mol
