Question

A substance has a molar heat of combustion of -810.4 kj/mol. when 0.285 mol of the substance is burned in a calorimeter containing 8.60 kg of water, the increase in water temperature is:

Answer 1

6.42 °C

Step-by-step explanation:

Q = mcΔT

Q = energy gain/release (J)

m = mass (kg)

c = specific heat capacity (J/°C/kg)

ΔT = change in temperature (°C)

Qs = n(ΔH°c)

Qs = energy gained/released from substance (kJ)

n = moles (mol)

ΔH°c = molar heat of combustion (kJ/mol)

m = 8.60

n = 0.285

ΔH°c = -810.4

c (of water) = 4184

Qs = 0.285(-810.4)

Qs = -230.964 (or -230964 J)

Q = 230964

230964 = (8.60)(4184)ΔT

230964 = 35982.4(ΔT)

ΔT = 6.4188... °C → 6.42 °C