Free Printable Thermo REVIEW

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Thermo REVIEW

Total questions: 25

Worksheet time: 1hrs 18mins

Name

Class

Date

What type of reaction is shown in the reaction pathway?

endothermic reaction

exothermic reaction

How do you calculate Enthalpy of a reaction?

ΔH = ΔH_products- ΔH_reactants

ΔT = q / mC

ΔG = ΔH -TΔS

E = mc²

Which statement is true regarding ENDOTHERMIC reactions?

Temperature change is positive and enthalpy change is positive

Temperature change is positive and enthalpy change is negative

Temperature change is negative and enthalpy change is positive

Temperature change is negative and enthalpy change is negative

The enthalpy change is a negative (-) value, what side of the equation will the energy value be on.

Reactants

Products

What type of reaction is shown in the reaction pathway?

endothermic reaction

exothermic reaction

In the Image, will the heat (+177.8 KJ) be a product or a reactant?

Product

Reactant

Define the term Exothermic by picking the correct statements. (Choose 3)

Products have less energy than the reactants

ΔH is negative

ΔH is positive

Energy is given out to the surroundings (temperature goes up).

products have more energy than the reactants

Define Endothermic by picking the correct statements. (Choose 3)

ΔH is positive

Energy is taken in from the surroundings (temperature goes down).

Energy is given out to the surroundings (temperature goes up).

· Products have less energy than the reactants

products have more energy than the reactants

Is this equation endo- or exo-thermic?

PCl₃ (s) + Cl₂ (g) --> PCl₅ (s) + energy

endothermic

exothermic

10.

As 120 g of hot milk cools in a mug, it transfers 20, 000 J of heat to the environment. What is the temperature change of the milk? The specific heat of milk is 2.6 J/g·°C. (Q=mcΔT)

64 °C

1.56 °C

640 °C

cannot be determined

11.

How much heat in KJ does an aluminum block absorb if 100.0 grams are heated from 25.0^oC to 50.0^oC? the specific heat of aluminum is 0.900J/g^oC

4.5 KJ

-4.5 KJ

2.25 KJ

-2.25 KJ

12.

If 25 J are required to change the temperature of 5.0 g of substance A by 2.0°C, what is the specific heat of substance A?

250 J/g C

10 J/g C

63 J/g C

2.5 J/g C

13.

A sample of iron receives 50.J of heat energy that raises the temperature of the iron by 25.0°C. If iron has a specific heat of 0.10 J/g°C, what is the mass of the iron sample?

25g

30g

20g

50g

14.

Based on the information in the table above, which of the following expressions gives the approximate ΔH° for the reaction represented by the following balanced chemical equation?

Fe2O3(s)+3 CO(g)→2 Fe(s)+3 CO2(g)

ΔH°rxn=[(0kJ/mol)+(−394kJ/mol)]−[(−826kJ/mol)+(−111kJ/mol)]

ΔH°rxn=[2(0kJ/mol)+ 3(−394kJ/mol)]−[(−826kJ/mol)+ 3(−111kJ/mol)]

ΔH°rxn=[(−826kJ/mol)+ 3(−111kJ/mol)]−[2(0kJ/mol)+ 3(−394kJ/mol)]

ΔH°rxn=[(−826kJ/mol)+(−111kJ/mol)]−[(0kJ/mol)+(−394kJ/mol)]

15.

Calculate the enthalpy of reaction (ΔH).

4CO_{2 (g)} + 6H₂O _(g) → 2C₂H_{6 (g)} + 7O_{2 (g)}

ΔH_f^o [CO_2(g)] = -393.5 kJ

ΔH_f^o[H₂O_(g)] = -241.8 kJ

ΔH_f^o [C₂H_6(g)] = -84.7 kJ

550.647 KJ/mol

2855.584 KJ/mol

-550.647 KJ/mol

-2855.584 KJ/mol

16.

Consider the following equations.

Mg_(s) + O_2(g) → MgO_(s) ∆H = –602 kJ

H_2(g) + O_2(g) → H₂O_(g) ∆H = –242 kJ

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

MgO_(s) + H_2(g) → Mg_(s) + H₂O_(g)

-844

-360

+360

+844

17.

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)

c – 4a – 5b

2a + 10b - c

4a + 5b - c

2a + 5b + c

18.

4 NH₃ (g) + 5 O₂ (g) ⟶ 4 NO (g) + 6 H₂O (g)

Using the following information, calculate ΔH for the reaction shown above:

N₂(g) + O₂ (g) ⟶ 2 NO (g) ΔH = -180.5 kJ

N₂(g) + 3 H₂ (g) ⟶ 2 NH₃ (g) ΔH = -91.8 kJ

2 H₂ (g) + O₂ (g) ⟶ 2 H₂O (g) ΔH = -483.6 kJ

256.0 kJ

-1628.2 kJ

-6387 kJ

None of these

19.

The enthalpy of reactions for the synthesis two oxides of phosphorus are:

P_4(s) + 3O_2(g) → P₄O_6(s) ΔH_f = –1600 kJ mol^–1

P_4(s) + 5O_2(g) → P₄O_10(s) ΔH_f = –3000 kJ mol^–1

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

P₄O_6(s) + 2O_2(g) → P₄O_10(s)

+4600

+1400

–1400

–4600

20.

What is the specific heat of an unknown substance if 100.0 g of it at 200.0 °C reaches an equilibrium temperature of 27.1 °C when it comes in contact with a calorimeter of water. The water weighs 75. g and had an initial temperature of 20.00 °C? (Specific heat of water is 4.18 J/g°C) (show your work)

0.111 J/g°C

1.29 J/g°C

0.129 J/g°C

22225.85 J

21.

A piece of metal with a mass of 32.8 g is heated to 100.5°C and dropped into 138.2 g of water at 20.0°C. The final temperature of the system is 30.2°C. What is the specific heat capacity of the metal? (show your work)

2.56 J/g°C

0.391 J/g°C

5.29 J/g°C

3.50 J/g°C

22.

What does $\Delta T$ represent?

$t_{f\ }-t_i$

$t_{i\ }-t_f$

t - celsius

celsius - t

23.

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

H₂O (l) + 44.0 kJ --> H₂O (g)

(Remember, coefficient of 1 = 1 mole)

207 kJ

9.36 kJ

206.8 kJ

9.362 kJ

24.

300 mL of water at 95 ºC are added to 700 mL of water at 62.8 ºC. What is the final temperature of the full liter of water?

50 ºC

85.6 ºC

72.5 ºC

94.2 ºC

25.

What mass of P₄ must be reacted to produce 5905 kJ of energy?
P₄ + 6Cl₂ --> 4PCl₃ + 2439 kJ

25.43 g

563.0 g

2.421 g

300.0 g

100 %

Thermo REVIEW

Total questions: 25

Worksheet time: 1hrs 18mins

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