Answer to Question #193705 in General Chemistry for Nicole

Question

Write the thermochemical equation for the following reactions that occur at constant pressure.

Example :

Decomposition of mercuric oxide HgO to mercury Hg and Oxygen O2 gas, requires 87.1 Kj of heat

 HgO(s) --> Hg(/) + O2(g)    ∆H= + 87.1 kJ(needs to absorb energy)

1. Combustion of hexane,C6H12 to carbon dioxide gas and water, releases 3923.9 kJ of heat.

2. Reaction between solid phosphorous, P4 and oxygen gas, produces P3O5 and 1640.1kJ of heat.

3. One mole ammonium nitrate (NH4NO) dissolves in water to produce aqueous ammonium ions and nitrate ions accompanied by the absorption of 28.1kJ of heat.

4. Formation of carbon dioxide gas from carbon (graphite) and oxygen yields 393.5 kJ of heat.

Answer 1

$2 C_6H_{14} + 19 O _{12} \to CO_2 + 14 H_2O \Delta H=-3,923.9kJ$