Red phosphorus reacts with liquid bromine in an exothermic reaction `:` `2P_((s))+3Br_(2(l))rarr2PBr_(3(g))` `Delta_(r)H^(@)=-243kJ`. Calculate the enthalpy change when `2.63g` of phosphorus with an excess of bromine in this way.

Explanation

To calculate the enthalpy change when 2.63 g of red phosphorus reacts with excess bromine, we can follow these steps:

### Step 1: Calculate the number of moles of phosphorus
The molar mass of phosphorus (P) is approximately 31 g/mol. We can calculate the number of moles using the formula:

\[ \text{Number of moles} = \frac{\text{mass (g)}}{\text{molar mass (g/mol)}} \]
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