Question

6. Answer the following questions regarding the reaction below. a. How many grams of hydrogen would be needed to produce 5.450 x 106 kJ of energy? Assume excess oxygen? How many grams of oxygen would be needed to produce 2.725 x 106 kJ of energy? Assume excess hydrogen? Determine the value of q for the formation of 6.542 grams of water. Determine the value of q for the conversion of 6.542 grams water into hydrogen and oxygen gas. b. c. d.

Answer 1

Solution:- (a) From balanced equation, 285.83 kJ of heat energy is produced when 1 mol of hydrogen is reacted.

We can calculate the grams of hydrogen gas used to produce of heat using dimensional analysis as:

5.450 * 10%J

5.450 10°k lmol2 2.02gH 285.83kJ molH

=

3.852 104gH2

(b) Part b could also be solved similar to part a.

2.725 10kJ(Q.5molo2, 32g0 285.83kJ molO

=

1.525 10 gO

(c) We can solve for q produced when 6.542 g of water are formed as:

1mol H2O ),-285.83k J 18.02gH201molH20

q =

103.8kJ

(d) Decomposition of water is an endothermic reaction and so the sign of heat for this will be positive,

lmolH20285.83k.J 18.02gH20 1molH2o

q = 103.8 kJ