Can somebody tell me how to do this? (1 Viewer)

[Dragonmaster262]

Q) Calculate the enthalpy change which occurs when 0.50 g magnesium is burned in air, 12.4 kJ of heat is released.

 

[lychnobity]

Q) Calculate the enthalpy change which occurs when 0.50 g magnesium is burned in air, 12.4 kJ of heat is released.

You're given quantity of heat = 12.4 kJ, let this be q

delta H = -q/(no. mol)

0.5g Mg = (0.5)/24.31 = 0.02mol

Delta H = -12.4/0.02 = 620 kJ/mol

(someone correct if I'm wrong, I'm a bit rusty)

 

[Dragonmaster262]

You're given quantity of heat = 12.4 kJ, let this be q

delta H = -q/(no. mol)

0.5g Mg = (0.5)/24.31 = 0.02mol

Delta H = -12.4/0.02 = 620 kJ/mol

(someone correct if I'm wrong, I'm a bit rusty)

The answer is supposed to be -1.2 x 10^3 kJ/mol

 

[Dragonmaster262]

Could anyone else please take the liberty of helping out? This question is pretty basic and help would be appreciated.

 

[xFusion]

i got the same answer as lychnobity.

 

[Dragonmaster262]

And people say that Conquering Chemistry is a must. This book has as many errors as Dot Point. Thanks anyways.

 

[Aerath]

And people say that Conquering Chemistry is a must. This book has as many errors as Dot Point. Thanks anyways.

The book is fairly decent - theory wise - for Preliminary. Just do questions from past school papers.