[girlyxgamer]

Hi, i am new to these forums.

i need help on a calorimetry problem:

CuSO4 -> Cu^2+ + SO4^-2

0.800 g of CuSO4 is dropped into a calorimeter with 43.0 g of water at an initial temperature of 18.3 degree C. As CuSO4 dissolves in water, the temperature rose to 20.2 degree C. What value is the heat enthalpy obtained from the data?

i know the answer is -68.2 kJ but i don't know how to get there.

this is as far as i got:

(43.0)(4.184)(20.2-18.3) = 341 J

please help and show step by step explanations please.

thanks

[ARGOS++]

Dear girlyxgamer;

341.8 J is the heat for 0.800 g CuSO4; what is in this moment the heat for 1 mole CuSO4?
Please don't round intermediate results.

Good Luck!
                    ARGOS⁺⁺

[girlyxgamer]

how do you convert it to 1 mol of CuSO4? thanks

[ARGOS++]

Dear girlyxgamer;

First: What is the molecular weight of CuSO₄?

Good Luck!
                    ARGOS⁺⁺

[girlyxgamer]

159.6 grams of CuSO4

[ARGOS++]

Dear girlyxgamer;

Perfect!

Now rephrase my first question:
341.8 J is the heat for 0.800 g CuSO₄; what is in this moment the heat for 1 mole (= 159.6 g/mol) CuSO₄?

Good Luck!
                    ARGOS⁺⁺

[girlyxgamer]

-341 j/.800 g CuSO4 * 159.6 g CuSO4

wow thanks very much, i'm already liking this forum. very helpful and detailed process you guys use to teach me 

[ARGOS++]

Dear girlyxgamer;

Correct!

You 're welcome!   ─   Soon again.

Good Luck!
                    ARGOS⁺⁺