Question

When a 1.0560 g benzoic acid sample was burned in a bomb calorimeter to establish the calorimeter constant, a temperature rise of 2.862 K was measured near 298K. Under similar conditions, a temperature rise of 2.416 K was measured when a 0.5863 g naphthalene sample was burned. Determine the calorimeter constant (in units of kJ/K) and the standard enthalpy of combustion for naphthalene at 298K. If we make the assumption that ∆H ≈∆U, is the ∆cHº value obtained from this experim

Answer 1

`C_(calorimeter)=7.14x10^(-4)kJ/K`

ΔcH
`=-337.14J/mol`

Step-by-step explanation:

Hello,

In this case, naphthalene has a Cp=156.1J/(mol*K) and the following equation must be applied to find the enthalpy of combustion (negative since it is about an outgoing form of energy) considering the given assumption (∆H ≈∆U)

ΔcH=Cp*ΔT

ΔcH
`=156.1*2.416K\\=-337.14J/mol`

For the calorimeter constant, we develop:

`C_(calorimeter)=0.5863gC_(10)H_8*(1molC_(10)H_8)/(128.17gC_(10)H_8) *156.1(J)/(mol*K)\\\\C_(calorimeter)=0.714J/K=7.14x10^(-4)kJ/K`

Best regards.