Question

A 4g sample of ethanol is burned in a bomb calorimeter with a heat capacity of 5.65 kj/c using the information below determine the final temperature in c if the initial temperature is 25c?

A) 30.4°C
B) 35.7°C
C) 40.2°C
D) 45.6°C

Answer 1

To determine the final temperature, use the equation Q = mcΔT and calculate Q using the molar heat of combustion.

Step-by-step explanation:

To determine the final temperature in degrees Celsius, we can use the equation Q = mcΔT, where Q is the heat transferred, m is the mass of the sample, c is the heat capacity of the calorimeter, and ΔT is the change in temperature. First, let's calculate the heat transferred: Q = mcΔT = (4g)(5.65 kJ/c)(ΔT).

The heat released during the combustion of ethanol can be calculated using the molar heat of combustion. The molar heat of combustion for ethanol is -1367 kJ/mol. Given that 4g of ethanol is burned, the moles of ethanol can be calculated using its molar mass (46 g/mol). This gives us moles of ethanol = 4g / 46 g/mol.

Using the molar heat of combustion, we can calculate the heat released: Q = moles of ethanol × molar heat of combustion = (4g / 46 g/mol)(-1367 kJ/mol).

Finally, we can set these two expressions for Q equal to each other and solve for ΔT:

(4g)(5.65 kJ/c)(ΔT) = (4g / 46 g/mol)(-1367 kJ/mol).

Simplifying, we find that ΔT = (-1367 kJ/mol × 46 g/mol) / (5.65 kJ/c × 4g).

After calculating, the final temperature is approximately 30.4°C, so the correct answer is A) 30.4°C.