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Enthalpy of rxn and Hess's Law

Total questions: 15

Worksheet time: 33mins

Name
Class
Date
1.

What type of reaction is shown in the graph?

a)

endothermic reaction

b)

exothermic reaction

2.

H2 + ½ O2 --> H2O + 285 kJ

is an example of a(n)

a)

Electrical equation

b)

Heat equation

c)

Thermochemical equation

3.

C+ O2 --> CO2 + 60kJ

what is the ΔH for the reaction?

a)

+60

b)

-60

c)

there is no way to know

4.

How do you calculate Enthalpy of a reaction?

a)

ΔH = ΔHproducts - ΔHreactants

b)

ΔT = q / mC

c)

ΔG = ΔH -TΔS

d)

E = mc2

5.
Endothermic reactions feel
a)
warm
b)
cold
6.

What is the Change in Enthalpy of Reaction for the decomposition of Sodium Bicarbonate?

NaHCO3(s) → Na2CO3(s) + H2O(g) + CO2(g)

a)

129.18 kJ/mol

b)

-818.52 kJ/mol

c)

-947.7 kJ/mol

d)

-1130.9 kJ/mol

7.

What is the Change in Enthalpy of Reaction for the Formation of Sodium Chloride?

Na(s) + Cl2(g) → NaCl(s)

a)

-821.8 kJ/mol

b)

-818.52 kJ/mol

c)

-410.9 kJ/mol

d)

-113.9 kJ/mol

8.

Did you hear about the man who got cooled to absolute zero?

a)

He's 0K now.

b)

He dead.

c)

Can't Happen!

d)

Yep... another science pun I don't understand

9.

What does letter W represent?

a)

Energy of reactants in the forward reaction

b)

Activation energy of forward reaction

c)

Energy of products in the forward reaction

d)

Enthalpy of the forward reaction

10.

What does letter T represent?

a)

Energy of reactants in the forward reaction

b)

Activation energy of forward reaction

c)

Energy of products in the forward reaction

d)

Enthalpy of the forward reaction

11.

What does letter C represent?

a)

Energy of reactants in the forward reaction

b)

Activation energy of forward reaction

c)

Reactants

d)

Activated complex

12.

Is this reaction endothermic or exothermic?

a)

The reaction is exothermic because energy of the products is less than energy of the reactants

b)

The reaction is exothermic because energy of the products is more than energy of the reactants

c)

The reaction is endothermic because energy of the products is less than energy of the reactants

d)

The reaction is endothermic because energy of the products is more than energy of the reactants

13.

The enthalpies of combustion of C(s), H2(g) and C4H9OH(l) (in kJmol-1) are as follows

C(s) + O2(g) -> CO2(g) ∆H=a

H2(g) + ½O2(g) -> H2O(l) ∆H=b

C4H9OH(l) + 6O2(g) -> 4CO2(g) + 5H2O(l) ∆H=c

What is the enthalpy change for the reaction shown below?

4C(g) + 5H2(l) + ½O2(g) -> C4H9OH(l)

a)

c – 4a – 5b

b)

4a + 5b - c

c)

2a + 10b - c

d)

2a + 5b + c

14.

The standard enthalpy changes of combustion of carbon, hydrogen and methane are shown in the table.

Which one of the following expressions gives the correct value for the standard enthalpy change of formation of methane in kJ mol–1?

C(s) + 2H2(g) → CH4(g)

a)

394 + (2 × 286) – 891

b)

–394 – (2 × 286) + 891

c)

394 + 286 – 891

d)

–394 – 286 + 891

15.
(Hess's Law)Calculate the ∆H for the following reaction: 2H2O  2H2O  + 1 O2 
You are given these two equations:
2H+  O2  2H2O            ∆H  =  -572 kJ
H2  +  O2    H2O2            ∆H  =  -188 kJ 
a)
∆H  =  -948 kJ 
b)
∆H  =  -196 kJ 
c)
∆H  =  -384 kJ 
d)
∆H  =  -188 kJ