Q cal = C cal * ΔT
= 5.23 KJ/°C *(29.8-23.7)°C
= 31.903 KJ
This heat is supplied by pentane
Molar mass of C₅H₁₂ = 5*MM(C) + 12*MM(H)
= 5*12.01 + 12*1.008
= 72.146 g/mol
mass of C₅H₁₂ = 0.1523 g
we have below equation to be used:
number of moles of C₅H₁₂,
n = mass of C₅H₁₂/molar mass of C₅H₁₂
=(0.1523 g)/(72.146 g/mol)
= 2.111 *10⁻³ mol
delta U = -Qcal /number of mol
= -31.903 KJ / 2.111*10⁻³ mol
= -15113 KJ/mol
