The tungsten used in filaments for light bulbs can be prepared from tungsten (VI) oxide by reduction with hydrogen at `1200^@C`
`WO_3(s) + 3H_2(g) W(s) + 3H_2O (g) , Delta H = 114.9 kJ`
`Delta H_f ` for `H_2O(g) = -214.8 kJ "mol"^(-1)` . Calculate `Delta H_f` for `WO_3(s)`.

Explanation

To calculate the enthalpy of formation (\( \Delta H_f \)) for tungsten (VI) oxide (\( WO_3(s) \)), we will follow these steps:

### Step 1: Write the given reaction and its enthalpy change
The reaction for the reduction of tungsten (VI) oxide with hydrogen is given as:
\[ WO_3(s) + 3H_2(g) \rightarrow W(s) + 3H_2O(g) \]
The enthalpy change for this reaction (\( \Delta H_1 \)) is:
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