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Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: diah on October 17, 2013, 03:42:35 PM

Title: Change in Enthalpy
Post by: diah on October 17, 2013, 03:42:35 PM

Given:
-number of grams of MgCl2 that was dissolved in water in a calorimeter
-initial temp and final temp in degrees C
-heat capacity of solution and calorimeter in J/degrees C

Asking:
What is the enthalpy change when 1.50 mol of MgCl2 dissolves in water?

I know I can take the initial temp and final temp to find delta T, but what equation do I use or what steps do I take to find the enthalpy change?

Title: Re: Change in Enthalpy
Post by: orgo814 on October 17, 2013, 05:41:01 PM

You have your heat capacity and temperature change, so you can solve for Q right? C = Q/delta T.

Given that you have grams, you can find moles and use the expression Q = (n) (delta U)... use the absolute value of that. Having delta U is important because you can now solve for the enthalpy change. H = U + PV... how can you make that expression useful to you?