How do you find the enthalphy change per mole of magnesium?

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Homework Statement


In this calorimetry experiment, O.5 grams of magnesium is dissolved in 100.0 ml (100.0g) of diluted HCL (0.1mol/L) at an initial temperature of 29.50 C. The final temperature is 46.18 C.

Q: Calculate the enthalpy change per mole of magnesium.


Homework Equations



I'm really confused about how will i get the the enthalpy change per mole for magnesium. Would it be the same as getting the enthalpy change per mole for magnesium chloride, because that's how i treated it and i don't think its the right answer. Can someone please help me?


The Attempt at a Solution



C) In this calorimetry experiment, O.5 grams of magnesium is dissolved in 100.0 ml (100.0g) of diluted HCL (0.1mol/L) at an initial temperature of 29.50 C. The final temperature is 46.18 C.

The enthalpy change per mole of magnesium:

mass of mg = 0.5 grams
Molar mass of mg = 24.21g/mol
moles of mg = (0.5grams)/(24.31g/mol)
= .0206 moles of Mg

H = q
(Mg dissolving) = (calorimeter water)

H = n Hsol and q=mc t

mHCL = 100grams

cwater = 4.18

T = 46.18-29.50 = 16.18

n Hsol = mc T

Hsol(mg)= (mc T)/n
= (100gramsX4.18 J/g C X16.68C)/(.0206)
= 338990.3092 Joules
= 338.99 KJ/mol
 

Answers and Replies

  • #2
Borek
Mentor
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I am not sure what you mean - you (correctly) calculated change per one mole of Mg consumed. That's it.
 

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