Question

are exothermic. The heat of reaction for the combustion of2 methylpentane, CHi is 993.6 kcal/mol. What is the heat of c kcal/gram How much heat will be given off if molar quantities of 2-methylpentane react according to the following equation? 2 C6Hi4+19 02 12 CO2+14 H20 kcal Submit Answer Retry Entire Group 5 more group attempts remaining

Answer 1

The heat of reaction for the combustion of 2-methylpentane is 993.6Kcal/mole
gram molar mass of 2-methyl pentane = 86g/mole
The heat of reaction for the combustion of 2-methylpentane in KCal/gram = 993.6KCal/86g/mole
                                                                         = 11.55KCal/gram
The heat of combustion of 1mole of C6H14 is -993.6Kcal/mole
But in this reaction 2 moles of C6H14 is participate
2C6H14 + 19O2 ----------> 12Co2 + 14H2O DH = 2moles*-993.6KCal/mole
                                             = -1987.2KCal

2Fe(s)+ O2(g) ---------> 2FeO(s)     DH = -544Kj
2Zn(s) + O2(g) --------> 2ZnO(s)     DH = -696.6KJ
(-)      (-)            (-)                 (+)        substract two equation

--------------------------------------------------------------
2ZnO(s) + 2Fe(s) --------> 2FeO(s) + 2Zn(s) DH = 152.6Kj

2FeO(s) + 2Zn(s) --------> 2ZnO(s) + 2Fe(s) DH = -152.6KJ
FeO(s) + Zn(s) --------> ZnO(s) + Fe(s) DH = -152.6/2KJ   = -76.3KJ

SnCl4(g) -------------> Sn(s, white) + 2Cl2(g)    DH = 472KJ

Sn(s, white) + 2Cl2(g) -----------> SnCl4(g)    DH = -472KJ