Free Printable AS energetics 1

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AS energetics 1

Total questions: 12

Worksheet time: 12mins

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Date

For which equation is the enthalpy change correctly described as an enthalpy change of formation?

2NO(g) $\rightarrow$ N2(g) + O2 (g)

2CO(g) + O2(g) $\rightarrow$ 2CO2(g)

H2O(l) + NaCl (s) $\rightarrow$ NaCl(aq)

K(s) + Mn(s) +2O2(g) $\rightarrow$ KMnO4(s)

Which equation has an. enthalpy change of reaction which corresponds to the standard enthalpy change of atomization of chlorine?

1/2 Cl2(g) $\rightarrow$ Cl(g)

1/2 Cl2(l) $\rightarrow$ Cl(g)

Cl2(g) $\rightarrow$ 2Cl(g)

Cl2(l) $\rightarrow$ 2Cl(g)

The equation for a reaction is shown.

H₂(g) + 1/2 O₂(g) → H₂O (l) ; ΔH = x kJ mol ^-1

It represents enthalpy change of formation only.

It represents enthalpy change of formation and combustion.

x is positive

x is negative

Hydrogen peroxide slowly decomposes into water and oxygen. The enthalpy change of reaction can be calculated using standard enthalpies of formation.

ΔH^ϴf(hydrogen peroxide(I)) = - 187.8 kJ/mol

ΔH^ϴf(water(I)) = - 285.8 kJ/mol

Using a Hess cycle, what is the enthalpy change of reaction for this decomposition?

2H₂O₂(l) → 2H₂O(l) + O₂ (g)

+ 98 kJ/mol

- 98 kJ/mol

- 196 kJ/mol

- 947.2 kJ/mol

Titanium occurs naturally as the mineral rutile, TiO₂. One possible method of extraction of titanium is to reduce the rutile by heating with carbon.

TiO₂(s) + 2C(s) → Ti(s) + 2CO(g)

The standard enthalpy changes of formation of TiO₂(s) and CO(g) are - 940 kJ/mol and - 110 kJ/mol respectively.

What is the standard enthalpy change of this reaction.

- 830 kJ/mol

- 720 kJ/mol

+ 720 kJ/mol

+ 830 kJ/mol

Skiers trapped by snowstorms use heat packs to keep warm. The heat may be generated by the reaction below.

4Fe(s) + 3O₂(g) → 2Fe₂O₃(s); ΔH^Θ = -1648 kJ/mol

What is the standard enthalpy change of formation of iron(III) oxide?

0 kJ/mol

-824 kJ/mol

-1648 kJ/mol

-3296 kJ/mol

What is the standard enthalpy change of combustion of propane-1-ol, in kJ/mol.

- 394 -286 - 303

303 - (4 x 286) - (3 x 394)

394 + 286 - 303

(3 x 394) + (4 x 286) +303

50 cm³ of 2.50 mol dm^-3 hydrochloric acid was placed in a polystyrene beaker of negligible heat capacity. Its temperature was recorded and then 50 cm³ of 2.50 mol dm^-3 NaOH at the same temperature was quickly added, with stirring. The temperature rose by 17 ºC.

The resulting solution may be considered to have specific heat capacity of 4.2 Jg^-1K^-1.

What is an approximately value for the molar enthalpy change of neutralization of hydrochloric acid and sodium hydroxide from this experiment?

$\frac{-\left(50\times4.2\times17\right)}{0.050\times2.5}$ J/mol

$\frac{-\left(50\times4.2\times17\right)}{0.10\times2.5}$ J/mol

$\frac{-\left(100\times4.2\times17\right)}{0.050\times2.5}$ J/mol

$\frac{-\left(100\times4.2\times17\right)}{50\times2.5}$ J/mol

What are P, Q and R?

P: ethanoic acid

P: sulfuric acid

Q: ammonia

Q: sodium hydroxide

R: potassium hydroxide

10.

In a calorimetric experiment 1.60 g of a fuel are burnt. 45.0% of the energy released is absorbed by 200 g of water. The temperature of the water rises from 18.0 °C to 66.0 °C.

What is the total energy released per gram of fuel burnt?

25100 J

55700 J

89200 J

143000 J

11.

Nitric oxide, NO, and bromine vapour react together according to the following equation.

2NO(g) + Br₂(g) → 2NOBr(g); ΔH = -23 kJ mol^-1

The reaction has an activation energy of + 5.4 kJ mol^-1.

What is the correct reaction pathway diagram for this reaction?