General Chemistry I Laboratory Manua), 2017 Revision 113 Hess\' Law Pre-Lab Name
ID: 580298 • Letter: G
Question
General Chemistry I Laboratory Manua), 2017 Revision 113 Hess' Law Pre-Lab Name: Date: Determine the }{ for the reaction shown below using standard heat of ormation values from your textbook. Fe(s) + 3/4O2(g) 1/2Fe,Ols) 1 ) For the reaction above, how much heat would be liberated by the combustion of 3.00 g of iron metal in excess oxygen? 2) what would be the final temperature of the calorimeter if its initial temperature were 23.0? 3) If 4.00 g of iron metal are reacted in a calorimeter with a heat capacity of 400.Explanation / Answer
1) Fe(s) <------> 3/4O2(g) + 1/2 Fe2O3(s)
Hrxn = Hf° (products) - Hf°(reactants)
=(1/2 × Hf°(Fe2O3)) - (1× Hf°(Fe) + 3/4 ×Hf°(O2))
=( -824.2kJ/mol) - (0)
= - 824.2kJ/mol
2) No of mole of Fe = 3g/55.845g/mol =0.05372
1mole of Fe combustion release 824.2kJ of heat
Heat liberated by 0.05372mol of Fe= (824.2kJ/1mol)×0.05372mol = 44.28kJ
3) No of mole of Fe = 4g/55.485g/mol =0.07209
H = -824.2kJ × 0.07209 = -59.42kJ
Heat absorbed by Calorimeter is q
q= -H
q = T × C
59.42kJ = T × 0.400J/
T = 59.42kJ/0.400kJ/
= 148.55
T = Final temperature - Initial temperature
148.55 = Final temperature - 23
Final temperature = 148.55 + 23
= 171.55
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