Question

Styrene, C₈H₈, is one of the substances used in the production of synthetic rubber. When styrene burns in oxygen to form carbon dioxide and liquid water under standard-state conditions at 25°C, 42.62 kJ are released per gram of styrene. Find the standard enthalpy of formation of styrene at 25°C. (Given: ΔH°[CO₂(g)]=−393.5kJ/mol, ΔH°[H₂O(l)]=−285.8kJ/mol, ΔH°[H₂O(g)]=−241.8kJ/mol)

Answer 1

The empirical formula for polystyrene is CH2.

Step-by-step explanation:

To find the empirical formula for polystyrene, we need to determine the mole ratios of carbon and hydrogen. From the combustion analysis, we find that the sample of polystyrene produced 0.00726 g of CO2 and 0.00148 g of H2O. To find the moles of carbon and hydrogen, we first convert the grams of CO2 and H2O to moles using their molar masses. Then, we divide the moles by the smallest value to get the mole ratios. In this case, the mole ratio of carbon to hydrogen is 1:2, so the empirical formula for polystyrene is CH2.