Question

Bantuin aq donk pr kimia.. skrg mepet bget nih.
dik : deltaHf° H2O(L) = -285,5 kj mol^-1
deltaHf° CO2(g) = -393,5 kj mol^-1
deltaHf° C3H8(g) = -103 kj mol^-1
a. hitunglah deltaH°c C3H8
b. berapa kalor Yg dilepas jika 10 gram C3H8 dibakar sempurna. (Ar C = 12; H 1)

Answer 1

C3H8 + 5 O2 → 3 CO2 + 4 H2O

a. ΔH°c = ∑ΔH produk - ∑ΔH reaktan
             = [(3 × ΔH CO2) + (4 × ΔH H2O)] - [ΔH C3H8 + (5 × ΔH O2)]
             = [(3 ×-393,5) + (4 × -285,5)] - [-103 + (5 × 0)]
             = - 2219,5 kJ/mol

b. mol C3H8 = 10 ÷ 44 = 0,23
   ΔH untuk 0,23 mol = - 2219,5 × 0,23 = - 504,43 kJ/mol