Calculate the heat evolved when 266 g of white phosphorous \( \left(\mathrm{P}_{4}\right) \) burns in air according to the equation: \( \mathrm{P}_{4}(s)+5 \mathrm{O}_{2}(\mathrm{~g}) \rightarrow \mathrm{P}_{4} \mathrm{O}_{10}(\mathrm{~s}) \quad \Delta H=-3013 \mathrm{~kJ} / \mathrm{mol} \)

To calculate the heat evolved when 266 g of white phosphorous (\( \mathrm{P}_{4} \)) burns in air, we need to follow these steps: 1. Determine the number of moles of white phosphorous (\( \mathrm{P}_{4} \)) present. 2. Use the given equation and the molar heat of reaction to calculate the heat evolved. Let's start by determining the number of moles of white phosphorous (\( \mathrm{P}_{4} \)) present: Given: Mass of white phosphorous (\( \mathrm{P}_{4} \)) = 266 g Molar mass of white phosphorous (\( \mathrm{P}_{4} \)) = 123.88 g/mol Number of moles of white phosphorous (\( \mathrm{P}_{4} \)) = Mass of white phosphorous / Molar mass of white phosphorous Let's calculate the number of moles of white phosphorous (\( \mathrm{P}_{4} \)) present. Calculate the value by following steps: - step0: Calculate: \(\frac{266}{123.88}\) - step1: Convert the expressions: \(\frac{266}{\frac{3097}{25}}\) - step2: Multiply by the reciprocal: \(266\times \frac{25}{3097}\) - step3: Reduce the numbers: \(14\times \frac{25}{163}\) - step4: Multiply: \(\frac{14\times 25}{163}\) - step5: Multiply: \(\frac{350}{163}\) The number of moles of white phosphorous (\( \mathrm{P}_{4} \)) present is approximately 2.147 moles. Now, let's calculate the heat evolved using the given equation and the molar heat of reaction. Calculate the value by following steps: - step0: Calculate: \(2.147\left(-3013\right)\) - step1: Multiply the numbers: \(-6468.911\) The heat evolved when 266 g of white phosphorous (\( \mathrm{P}_{4} \)) burns in air is approximately -6469 kJ.