Test tasks

 

 

1. In the presence of bright light, hydrogen and chlorine react explosively. One step in the reaction is shown below

H2(g) + Cl (g) → HCl(g) + H(g)

The enthalpy change for this step can be represented as
A. (H-H bond enthalpy) + (Cl-Cl bond enthalpy)
B. (H-H bond enthalpy) - (Cl-Cl bond enthalpy)
C. (H-H bond enthalpy) + (H-Cl bond enthalpy)
D. (H-H bond enthalpy) - (H-Cl bond enthalpy)
2. The enthalpy of combustion of methanol is –727 kJ mol–1. What mass of methanol has to be burned to produce 727 kJ?
A. 3,2 g
B. 32,0 g
C. 72,7 g
D. 727,0 g
3. If a reaction is exothermic,
A. It takes more energy to break the bonds of the reactants than is released when the bonds in the products are formed
B. More energy is released when the bonds in the products are formed than is used to break the bonds in the reactants
C. The same amount of energy is used to break the bonds of the reactants as is released D. when the bonds in the products are formed
E. The temperature goes down
4. When 1.42 g of iron reacts with 1.80 g of chlorine, 3.22 g of FeCl2(s) and 8.60 kJ of heat is produced. What is the enthalpy change for the reaction when 1 mole of FeCl2(s) is produced?
A. ΔH = −349 kJ
B. ΔH = −330 kJ
C. ΔH = −338 kJ
D. ΔH = −357 kJ
5. In terms of potential energy, PE, which expression defines the heat of reaction for a chemical change?
A. PEproducts – Pereactants
B. PEreactants – Peproducts
C. PE products/ PE reactants
D. PE reactants/ PE products
6. One reaction that methane undergoes with chlorine is:

CH4(g) + 3Cl2(g) → CHCl3(g) + 3 HCl(g)

Using average bond energies calculate the enthalpy change for this reaction.
A. -2110 kJ,
B. -80 kJ
C. -92.22 kJ
D. -339kJ
7. Calculate the enthalpy change from bond energies for each of these reactions:

2H2O(g) → 2H2(g) + O2(g)
A. +544 kJ
B. +824 kJ
C. +509 kJ
D. +128 kJ
8. If a reaction is endothermic,
A. The temperature increases
B. It takes more energy to break the bonds of the reactants than is released when the bonds in the products are formed
C. More energy is released when the bonds in the products are formed than is used to break the bonds in the reactants
D. The same amount of energy is used to break the bonds of the reactants as is released when the bonds in the products are formed
9. Use bond energies to estimate the enthalpy change for the combustion of butane.
C4H10(g) + 13/2O2(g) → 4CO2(g) + 5H2O(g)
A. -2110 kJ,
B. -80 kJ
C. -92.22 kJ
D. -339kJ
10. Calculate the enthalpy change from
bond energies for each of these reactions:
2H2(g) + O2(g) → 2H2O(g)
A. -544 kJ
B. -824 kJ
C. -509 kJ
D. -128 kJ
11. How much heat is produced by the combustion of 125 g of acetylene?
A. 6.20 × 104 kJ
B. 6.25 × 103 kJ
C. 6.25 × 104 kJ
D. 6.55 × 102 kJ
12. The reaction of 1.0 mol of C to form carbon monoxide in the reaction

2C(s) + O2(g) → 2CO(g)

releases 113 kJ of heat. How much heat will be released by the combustion of 100 g of C according the above information?
A. 940 kJ
B. 1500 kJ
C. 25.9 kJ
D. 26.0 kJ
13. Calculate the enthalpy change from bond energies for each of these reactions:

H2(g) + F2(g) → 2HF(g)
A. -544 kJ
B. -824 kJ
C. -128 kJ
D. -509 kJ
14. Which element is least likely to undergo a chemical reaction?
A. lithium
B. fluorine
C. carbon
D. neon
15. 26 g of water at 18ºC are mixed with 49 g of water at 70ºC. Find the final temperature of the system.
A. 52ºC
B. 55.7ºC
C. 53ºC
D. 50.4ºC
16. Which compound is an electrolyte?
A. H2O
B. H3PO4
C. C2H6
D. CH3OH
17. When 1.0 mole of ethanol (C2H5OH) is burned, it releases -1367 kJ. How Much heat is released if 50 g of ethanol is burned?
A. 940 kJ
B. 1500 kJ
C. 25.9 kJ
D. 26.0 kJ
18. Which form of energy is associated with the random motion of the particles in a sample of water?
A. chemical energy
B. nuclear energy
C. electrical energy
D. thermal energy
19. 75.0 g of water at 30ºC are mixed with 83.8 g of a solid metal at 600ºC. The final temperature of the system is 50ºC. What is the specific heat capacity of the metal?
A. 0.136 J/g oC, Tungsten
B. 0.123 J/g oC, Tungsten
C. 0.335 J/g oC, Tungsten
D. 0.489 J/g oC, Tungsten
20. What occurs when Cr3+ ions are reduced to Cr2+ ions?
A. Electrons are lost and the oxidation number of chromium increases.
B. Electrons are lost and the oxidation number of chromium decreases.
C. Electrons are gained and the oxidation number of chromium increases.
D. Electrons are gained and the oxidation number of chromium decreases.