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1. 1) When butane gas, C 4 H 10 , burns in oxygen gas, O 2 , to form carbon diox

ID: 796626 • Letter: 1

Question

1.       1)  When butane gas, C4H10, burns in oxygen gas, O2, to form carbon dioxide gas, CO2, and gaseous water, 2845 kJ of thermal energy is evolved per mole of butane burned.

a.       Write the thernochemical equation for the reaction using whole number coefficients.

b.      Calculate the thermal energy evolved when 25.0 g of butane is burned.

2.       2) A 100.0 g sample of water at 25.30 oC was placed in an insulated cup. Then, 45.00 g of lead pellets at 100.00 oC was added. The final temperature of the water was 34.34 oC. What is the specific heat of lead?

Explanation / Answer

a) C4H10 + 13/2 O2   ------> 4CO2 + 5H2O

   thermal energy= 2845 kJ


b) 58 g of butane reacted 2845 KJ of energy released

    25 g of butane reacted =(2845/58)*25=1226.29 KJ of energy released


c)heat gained bu water= heat lost by lead pellects

   100*4.18*(34.34-25.3)=45*Cp*(100-34.34)

   Cp=1.28 J/g C

   specific heat of lead=1.28 J/g C