Consider the following balanced chemical equation for the oxidation of mercury:

ID: 563900 • Letter: C

Question

Hg () + O2 (g) 2 HgO (s) rH° = 182 kJ/molrxn at at 25°C

If 0.500 mol of HgO (s) was produced in an experiment performed under constant pressure

conditions, what do we know about the heat involved in this experiment?

a. q = 45.5 kJ

b. q = +45.5 kJ

c. q = +364 kJ

d. q = 364 kJ

Consider the following balanced chemical equation:

2 CF3 () + 2 O2 (g) C2O (g) + 3 OF2 (g) rH° > 0 ( used for next 3 question)

7What do we know about the standard formation enthalpy (fH°) of liquid oxygen, O2()?

a. fH° < 0

b. fH° = 0

c. fH° > 0

d. fH° = BDEH°

8. If the reaction was performed using liquid oxygen, O2(), instead of gaseous oxygen, then…

a. … a smaller amount of energy in the form of heat would be absorbed by the system.

b. … a smaller amount of energy in the form of heat would be released by the system.

c. … a larger amount of energy in the form of heat would be absorbed by the system.

d. … a larger amount of energy in the form of heat would be released by the system.

9. If the reaction was performed using liquid oxygen, O2(), instead of gaseous oxygen, then…

a. … more work would be done on the system.

b. … more work would be done by the system.

c. … less work would be done on the system.

d. … less work would be done by the system.

Ans 1 :a) -45.5 KJ

The reaction shows the formation of 2 mol of HgO , with the heat of reaction as -182 KJ/mol

Now here the heat of reaction for 0.500 mole of HgO formation will be : ( 0.500 x -182) / 2

= -45.5 KJ

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