30. Part A The value of H° for the reaction below is -482 kJ. Calculate the heat

Question

30. Part A

The value of H° for the reaction below is -482 kJ. Calculate the heat (kJ) released to the surroundings when 14.0 g of CO (g) reacts completely.

2CO (g) + O2 (g) 2CO2 (g)

31. Part A

The value of H° for the reaction below is -126 kJ. The amount of heat that is released by the reaction of 10.0 g of Na2O2 with water is ________ kJ.

2Na2O2 (s) + 2H2O (l) 4NaOH (s) + O2 (g)

32. Part A

The value of H° for the reaction below is -72 kJ. ________ kJ of heat are released when 3.0 mol of HBr is formed in this reaction.

H2 (g) + Br2 (g) 2HBr (g)

Explanation / Answer

30)

2CO (g) + O2 (g) 2CO2 (g)

MW of CO = 28 g/mol

m = 14 g

mol = mass/MW = 14/28 = 0.5

Hrxn = -482 kJ for 2 mol of CO

therefore for 0.5

0.5/2 * -482 = -120.5 kJ

31.

2Na2O2 (s) + 2H2O (l) 4NaOH (s) + O2 (g) H = -126

m = 10.0 Na2O2

MW of Na2O2 = 77.98

mol = mass/MW = 10.0 /77.98 = 0.1282 mol

2 mol fo Na2O2 will produce -126 kJ

therefore

0.1282 mol will produce--> -126*0.1282/2 = -8.08 kJ

32

H = -72 kJ for 2 mol

therefore for

n = 3 mol

you should have

3/2*Hrxn = 1.5*-72 = -108 KJ

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