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Thermochemistry

Total questions: 21

Worksheet time: 32mins

Name
Class
Date
1.

The potential energy diagram of a reaction is shown. Which statement below is correct relating to this reaction?

a)

#1 represents the enthalpy change for this exothermic reaction.

b)

#2 represents the enthalpy change for this endothermic reaction.

c)

#3 represents the enthalpy change for this endothermic reaction.

d)

#4 represents the enthalpy change for this exothermic reaction.

2.

The reaction of calcium chloride and water in the hot pack

tindak balas antara kalsium klorida dengan air dalam pek panas

a)

releases water/ membebaskan air

b)

releases heat/ membebaskan haba

c)

absorbs water/ menyerap air

d)

absorbs heat/ menyerap haba

3.
The specific heat of aluminum is 0.21 J/g°C.  How much heat(Q) is released when a 10 g piece of aluminum foil is taken out of the oven and cools from 100° to 50°?
a)
105 J
b)
10.5 J
c)
1.05 J
d)
0.105 J
4.
If the enthalpy ter (ΔH) is negative the reaction is ____.
a)
Endothermic
b)
Exothermic
c)
Neutral
5.
How much heat does an aluminum block absorb if 10.00 grams ae heated from 25.0oC to 50.0oC? the specific heat of aluminum is .900J/goC
a)
450
b)
-450
c)
225
d)
-225
6.

A student must use 225 g of hot water in a lab procedure. If the specific heat of water is 4.184 J/g°C Calculate the amount of heat required to raise the temperature of water from 20.0 C to 100.0 C.

a)

94140 J

b)

75312 J

c)

18828 J

d)

0.672 J

7.

The specific heat of a substance (C), whose units are J/g°C, is defined as

a)

The number of Joules required to raise the temperature of 1 gram of the substance 1 °C.

b)

The change in temperature when you add 1 Joule of energy.

c)

The number of grams created when the substance cools down 1°C.

d)

How hot or cold that specific amount of substance is.

8.

Is the following change of state an endothermic process or an exothermic process? H2O(l) + E --> H2O(g)

a)

Exothermic

b)

Endothermic

c)

Neither endothermic or exothermic

d)

Both endothermic and exothermic

9.

According to the diagram, what is ΔH for the reaction?

a)

80 kJ

b)

-80 kJ

c)

240 kJ

d)

-160 kJ

10.

What is the specific heat of a 230 g metal that takes 3.1 kcal to heat from 25 *C to 83*C

a)

0.0023 cal /g *C

b)

0.23 cal /g *C

c)

3400 cal /g *C

d)

3.4 cal / g*C

11.

How much energy must be used to produce 4.75 mol of gaseous water?

H2O (l) + 44.0 kJ --> H2O (g)

a)

209 kJ

b)

9.26 kJ

c)

206 kJ

d)

9.36 kJ

12.

Using the equations below:


C(s) + O2(g) → CO2(g) ∆H = –390 kJ

Mn(s) + O2(g) → MnO2(s) ∆H = –520 kJ


what is ∆H (in kJ) for the following reaction?


MnO2(s) + C(s) → Mn(s) + CO2(g)

a)

910

b)

130

c)

-130

d)

-910

13.

The following equations show the oxidation of carbon and carbon monoxide to carbon dioxide.


C(s) +O2(g) CO2(g) ΔH = –x kJ mol–1

CO(g) + O2(g) CO2(g) ΔH = –y kJ mol–1


What is the enthalpy change, in kJ mol–1, for the oxidation of carbon to carbon monoxide?


C(s) + O2(g) CO(g)

a)

x + y

b)

-x - y

c)

y - x

d)

x - y

14.

The standard enthalpy change of formation values of two oxides of phosphorus are:


P4(s) + 3O2(g) → P4O6(s) ΔHf = –1600 kJ mol–1

P4(s) + 5O2(g) → P4O10(s) ΔHf = –3000 kJ mol–1


What is the enthalpy change, in kJ mol–1, for the reaction below?


P4O6(s) + 2O2(g) → P4O10(s)

a)

+4600

b)

+1400

c)

–1400

d)

–4600

15.

Match the definition below to the correct term.

The enthalpy change that takes place when one mole of a compound is formed from its elements in their standard states under standard conditions.

a)

The enthalpy of neutralisation

b)

The enthalpy of combustion

c)

The enthalpy of formation

d)

The enthalpy of reaction

16.

Which of the following represent the enthalpy change of atomization?

a)

O2(g) → 2 O(g)

b)

Mg(s) → Mg(g)

c)

Mg(s) + Cl2(g) → MgCl2(s)

d)

Ca(g) → Ca2+(g) + 2 e

17.

which of the following represent the enthalpy change of hydration?

a)

Mg(s) → Mg2+(g)

b)

Mg(s) → Mg2+(g) + 2 e

c)

Cl2(g) + (aq)→ 2Cl(aq)

d)

Mg2+(g) → Mg2+(aq)

18.

MgCl2(s) ---> Mg2+(g) + 2Cl-(g)

This equation represents

a)

Enthalpy of hydration

b)

Enthalpy of solution

c)

Lattice enthalpy of dissociation

d)

Lattice enthalpy of formation

19.

Which of the following equations represents the enthalpy change of combustion?

a)

2C4H10(g) +13O2(g) → 8CO2 (g) + 10H20(g)

b)

C4H10(g) +13/2O2(g) → 4CO2 (g) + 5H20(g)

c)

C4H10 + 9/2O2 = 4CO (s)+ 5H2O

d)

C4H10 + 5/2O2 = 4C(s) + 5H2O(g)

20.

How do you calculate the Enthalpy of Reaction?

a)

ΔH = ΔHproducts - ΔHreactants

b)

ΔG = ΔH -TΔS

c)

ΔT = q / mC

d)

E = mc2

21.

HfinalH_{final}   > HinitialH_{initial}  means _____

a)

change of enthalpy is positive and system absorbs heat

b)

change of enthalpy is negative and system absorbs heat

c)

change of enthalpy is positive and system loses heat

d)

change of enthalpy is negative and system loses heat