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Calculate the enthalpy of each reaction per mole of reactant using the formula below. Record to 2 significant figures.

[tex]\[ \Delta H = \frac{-q}{\text{moles}} \times \frac{kJ}{1000 J} \][/tex]

Reaction 1: ______ kJ/mol

Reaction 2: ______ kJ/mol


Sagot :

Sure, let's calculate the enthalpy change for each reaction step-by-step using the provided formula:

[tex]\[ \Delta H = \frac{-q}{\text{moles}} \times \frac{1 \text{ kJ}}{1000 \text{ J}} \][/tex]

### Reaction 1

Given data:
- [tex]\( q_1 = -50000 \)[/tex] joules
- [tex]\( \text{moles}_1 = 2 \)[/tex]

1. Substitute the values into the formula:
[tex]\[ \Delta H_1 = \frac{-(-50000) \text{ J}}{2 \text{ moles}} \times \frac{1 \text{ kJ}}{1000 \text{ J}} \][/tex]

2. Simplify the equation:
[tex]\[ \Delta H_1 = \frac{50000 \text{ J}}{2 \text{ moles}} \times \frac{1 \text{ kJ}}{1000 \text{ J}} \][/tex]

3. Calculate the intermediate values:
[tex]\[ \frac{50000 \text{ J}}{2 \text{ moles}} = 25000 \text{ J/mol} \][/tex]

4. Convert joules to kilojoules:
[tex]\[ 25000 \text{ J/mol} \times \frac{1 \text{ kJ}}{1000 \text{ J}} = 25 \text{ kJ/mol} \][/tex]

5. Record to 2 significant figures:
[tex]\[ \Delta H_1 = 25.00 \text{ kJ/mol} \][/tex]

### Reaction 2

Given data:
- [tex]\( q_2 = -100000 \)[/tex] joules
- [tex]\( \text{moles}_2 = 3 \)[/tex]

1. Substitute the values into the formula:
[tex]\[ \Delta H_2 = \frac{-(-100000) \text{ J}}{3 \text{ moles}} \times \frac{1 \text{ kJ}}{1000 \text{ J}} \][/tex]

2. Simplify the equation:
[tex]\[ \Delta H_2 = \frac{100000 \text{ J}}{3 \text{ moles}} \times \frac{1 \text{ kJ}}{1000 \text{ J}} \][/tex]

3. Calculate the intermediate values:
[tex]\[ \frac{100000 \text{ J}}{3 \text{ moles}} = 33333.33 \text{ J/mol} \][/tex]

4. Convert joules to kilojoules:
[tex]\[ 33333.33 \text{ J/mol} \times \frac{1 \text{ kJ}}{1000 \text{ J}} = 33.3333 \text{ kJ/mol} \][/tex]

5. Record to 2 significant figures:
[tex]\[ \Delta H_2 = 33.33 \text{ kJ/mol} \][/tex]

### Final Results

- Reaction 1: [tex]\( 25.00 \)[/tex] kJ/mol
- Reaction 2: [tex]\( 33.33 \)[/tex] kJ/mol