Heat Equation help... (1 Viewer)

[marcquelle]

Q, 100g of water is heated to 25°Cby 1.8g of Ethanol

Calculate the;
1, Joules of energy required to heat the water.
2, How much energy is there per gram of ethanol
3, The energy per mol of Ethanol fuel



1, ΔH= mCΔT
C = 4.18 Jg-1K-1
m = 100g
ΔT = 22.5

=100 x 4.18 x 22.5
= 9405J

2, ΔH=9405 required 1.8g Ethanol
=9405/1.8
ΔH=5225J 1g of Ethanol

3, C2H5OH

C=2x12=24
H=6x1 = 6
O=1x16 = 16
46g = 1mol of Ethanol
5225x46=240350J per mol of Ethanol

. .

Have I calculated this right, if not can you correct me.

 

[marcquelle]

bump

 

[midifile]

Yep. But there are three problems (but I think they are just typos)

In the question you say it is heated to 225oC. Did you mean to say the temp increased by 25oC?

And also when you were working out the molar mass of ethanol you said that 6x1=1 and that the mass of oxygen was 1 (although its 16). But you got the correct overall molar mass, so I'm pretty sure it was just a typo.

Oh and also in question 3 you wrote to calculate the energy per molecule (but im pretty sure you meant mole)

Apart from that its correct

 

[marcquelle]

opps my bad yeah they were typos lol
i'll fix them