Final answer:
The final temperature of the calorimeter after the combustion of dimethylphthalate is calculated to be 25.08°C, by converting the mass of the substance to moles, using the heat of combustion to find the heat released, and then using the calorimeter's heat capacity to find the temperature change.
Step-by-step explanation:
To calculate the final temperature of the calorimeter after the combustion of dimethylphthalate, we need to use the information provided regarding the heat of combustion (ΔHcomb) and the mass of the substance combusted.
First, we convert the mass of dimethylphthalate (1.09 g) to moles using its molecular weight (C10H10O4, 194.19 g/mol):
moles = 1.09 g / 194.19 g/mol = 0.00561 mol
Next, we use the ΔHcomb value to find the amount of heat released:
heat released (q) = moles × ΔHcomb = 0.00561 mol × -4685 kJ/mol = -26.30 kJ
Now, applying the formula q = Ccalorimeter × ΔT to find the temperature change (ΔT):
× ΔT = q / Ccalorimeter
ΔT = -26.30 kJ / 7.35 kJ/°C = -3.58°C
The temperature change is negative because heat is being released (exothermic reaction). However, since we are interested in the increase in the temperature of the calorimeter, we take the absolute value:
ΔT = 3.58°C
Finally, we add this temperature change to the initial temperature to find the final temperature:
Tfinal = Tinitial + ΔT = 21.5°C + 3.58°C = 25.08°C
Answer: The final temperature of the calorimeter is 25.08°C. The closest option is b) 23.8°C, but the calculated temperature does not match exactly. This could be due to rounding during the calculation or a discrepancy in the options provided.