Energy Changes in Chemical Reactions (4)

Example of thermochemical equation shows an exothermic reaction

Mg(s) + H2SO4(aq) → MgSO4(aq) + H2(g) ΔH = -467 kJ mol−1

Formula to calculate heat of reaction, ΔH

The result of an exothermic reaction between magnesium, Mg and sulphuric acid, H2SO4

Forming magnesium sulphate, MgSO4 and hydrogen gas, H2 is an exothermic reaction

Heat that is released when 1 mole of Mg reacts with 1 mole of H2SO4 to form 1 mole of MgSO4 and 1 mole of H2 gas

467 kJ of heat is released to the surroundings

The temperature of the mixture for the exothermic reaction between magnesium, Mg and sulfuric acid, H2SO4

During the reaction, the temperature of the mixture increases

The total energy content of the products (MgSO4 and H2)

- Is lower than the total energy content of the reactants (Mg and H2SO4) - Therefore, ΔH is negative

The result of endothermic reaction between nitrogen gas, N2 and oxygen gas, O2

Forming nitrogen monoxide gas, NO is an endothermic reaction

The total of heat energy that is absorbed from the surroundings when 1 mole of N2 gas reacts with 1 mole of O2 gas to form 2 moles of NO gas

180 kJ heat energy is absorbed from the surroundings

The temperature of the mixture for the reaction between nitrogen gas, N2 and oxygen gas, O2

During the reaction, the temperature of the mixture decreases

Jumlah kandungan tenaga hasil tindak balas (NO)

- Jumlah kandungan tenaga hasil tindak balas (NO) lebih tinggi daripada jumlah kandungan tenaga bahan tindak balas (N2 dan O2) - Oleh itu, ΔH bertanda positif

Chemistry

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Energy Changes in Chemical Reactions (4)

Energy Changes in Chemical Reactions (4)