Question

question 4 and 5 are regarding enthalpies. please help with full calculations.

4. Uivell the following reactions: S(s) + O2(g) → SO,(g) AH = -297 kJ/mol SO2(g) + 120,(g) → SO,(g) AH = -141 kJ/mol calculate the AH for the reaction: S(s) +202(g) → SO2(g) 5. AH®,for Co, is -393.5 kJ/mol. Calculate the heat released by the burning of 0.327 g of carbon to form carbon dioxide. (Hint: start by writing the combustion equation!)

Answer 1

4.

Equation 1:

S(s) +0,(g) → SO,() AH = -297 kJ/mol

Equation 2:

Jow/fx Ibl-= HV (8)'os (8) 0% +(8) os

Enthalpy is a state function.

Adding equation 1 and equation 2 yields

S(s) + 3/2O₂(g)$\rightarrow$SO₃(g) $\Delta H$ = [- 297 + (-141)] kJ/mol = - 438 kJ/mol

Hence, the $\Delta H$ of the reaction = - 438 kJ/mol

5.

Mass of carbon = 0.327 g

Molar mass of carbon = 12 g/mol

Hence, moles of carbon = mass of carbon/molar mass of carbon

                                       = 0.327 g/12 g/mol

                                       = 0.0272 mol

C + O₂$\rightarrow$CO₂

Thus, 1 mol of C forms 1 mol of CO₂

Therefore, 0.0272 mol of C forms 0.0272 mol of CO₂

Now, heat released on formation of 1 mol of CO₂ = -393.5 kJ

Therefore, heat released on formation of 0.0272 mol of CO₂ = 0.0272 mol x -393.5 kJ/mol = -10.7 kJ