Two calorimeters each contain 1.4L of water and have a temperature of 26°C

In the first calorimeter, you burn a sample of candle wax and determine that 108.2kJ of energy is released. In the second calorimeter, you have to burn 5.4g of candle wax to raise the temperature of the water from 26°C to 53°C.
What is the mass of the candle wax used in the first calorimeter?

First, I did some conversions:

1.4L = 1400mL = 1400g (due to something about the equal density of water (1g/mL)

108.2kJ = 108200J

-And the specific heat capacity of water is 4.184 J/g°C

ΔT = Tf - Ti = 53°C - 26°C = 27°C

So I started off with (for the second calorimeter):

Q = mcΔT
Q = (1400g)(4.184J/g°C)(27°C)
Q = 160000J of thermal energy absorbed by the water, and released by the burning of the candle wax

Then...

-160000J -> 5.4g
-108200J -> x
x = 3.69g of candle wax was used in the first calorimeter

Is this correct?

Yes, your calculation is correct. To find the mass of the candle wax used in the first calorimeter, you used the equation Q = mcΔT, where Q is the thermal energy released by burning the candle wax, m is the mass of the water, c is the specific heat capacity of water, and ΔT is the change in temperature.

You correctly converted the volume of water from 1.4L to 1400g, as water has a density of 1g/mL. You also correctly converted the energy released from 108.2 kJ to 108200 J.

For the second calorimeter, you calculated the energy absorbed by the water to be 160000J based on the mass of the water, the specific heat capacity of water, and the change in temperature.

To find the mass of the candle wax used in the first calorimeter, you set up a proportion using the energy absorbed by the water in the second calorimeter and the mass of the wax used in the second calorimeter.

So, your final answer is that the mass of the candle wax used in the first calorimeter is 3.69g.