Thermochemistry-heat of reaction

[Jm4872]

Homework Statement

What will be the final temperature of the water in an insulated container as the result of passing 5.00 of steam at 100.0 into 100.0 of water at 27.0?

Homework Equations

q=mct
q=nH

The Attempt at a Solution

I am completely lost as to how to solve for final temperature, I attempted it, but it didn't work, this is what I did.

n=5.00g/(18.02g/mol)=0.277 mol

q=(0.277 mol)*(40.6KJ/mol)=11.27KJ
11.27KJ=mct
11.27KJ=(100g)*(4.18)*(Tf-27)
(11.27/418)=Tf-27
Tf=(0.02696)+27=27.0

can someone please help, I am so lost :( I don't understand what it is that I'm doing wrong

 

[Borek]

passing 5.00 of steam at 100.0 into 100.0 of water at 27.0?

5 of what, 100 of what, 100 of what, 27 of what?

 

[Jm4872]

5 of what, 100 of what, 100 of what, 27 of what?

oops, I didn't realize that the values didn't show up.

it should be 5.00g, 100degrees celcius, 100.0g and 27 degrees celcius

 

[Borek]

11.27KJ=(100g)*(4.18)*(Tf-27)

4.18 of what?

 

[DeeNos]

or what I'm missing.



It appears that you are on the right track with your calculations, but there are a few things that need to be adjusted. First, the value for the specific heat capacity of water should be 4.18 J/g*K, not 4.18 KJ/mol as you have used. This will give you a more accurate value for the final temperature. Additionally, you have used the specific heat capacity of water, but you should be using the specific heat capacity of steam (2.01 J/g*K) since the initial substance is steam.

Secondly, the value for the enthalpy of vaporization (H) should be used in the calculation, as this is the amount of energy required to convert 1 mole of steam into water at the same temperature. In this case, the equation should be q = nH, where n is the number of moles of steam (0.277 mol) and H is the enthalpy of vaporization of water (40.6 kJ/mol).

Finally, once you have calculated the total amount of heat (q) that is transferred from the steam to the water, you can use the equation q = mct to solve for the final temperature of the water. Make sure to use the correct values for mass (100.0 g) and specific heat capacity (4.18 J/g*K) of water in this equation.

Overall, your approach is correct but some adjustments need to be made in order to get a more accurate final temperature. I hope this helps clarify the concept of thermochemistry and heat of reaction for you. Keep practicing and don't hesitate to ask for help if you are still struggling.