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padilas [110]
3 years ago
14

The reaction of hydrogen(g) with fluorine(g) to form hydrogen fluoride(g) proceeds as follows: H2(g) + F2(g) 2 HF(g) When 0.647

grams of H2(g) react with sufficient F2(g) , 174 kJ of energy are evolved . What is the value of H for the chemical equation given? ΔHrxn = kJ
Chemistry
1 answer:
Nata [24]3 years ago
6 0

<u>Answer:</u> The value of \Delta H for the reaction will be -537 kJ

<u>Explanation:</u>

To calculate the number of moles, we use the equation:

\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}

Given mass of hydrogen gas = 0.647 g

Molar mass of hydrogen gas = 2 g/mol

Putting values in above equation, we get:

\text{Moles of hydrogen gas}=\frac{0.647g}{2g/mol}=0.324mol

We are given:

Energy released for 0.324 moles of hydrogen reacted is 174 kJ

For the given chemical reaction:

H_2(g)+F_2(g)\rightarrow 2HF(g)

By Stoichiometry of the reaction:

When 0.324 moles of hydrogen gas is reacted, the energy evolved is 174 kJ

So, when 1 mole of hydrogen gas will react, the energy evolved will be = \frac{174kJ}{0.324mol}\times 1mol=537kJ

<u>Sign convention of heat:</u>

When heat is absorbed, the sign of heat is taken to be positive and when heat is released, the sign of heat is taken to be negative.

Hence, the value of \Delta H for the reaction will be -537 kJ

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