PE diagrams and Heat of Reaction

1)    Which equation shows conservation of mass and energy for a reaction at 101.3 kPa and 298 K?

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1)    According to Table I, which equation represents a change resulting in the greatest quantity of energy released?

• 1. 2C(s) + 3H₂(g) → C₂H₆(g)

• 1. 2C(s) + 2H₂(g) → C₂H₄(g)

• 1. N₂(g) + 3H₂(g) → 2NH₃(g)

• 1. N₂(g) + O₂(g) → 2NO(g)

1)    According to Reference Table I, which statement best describes the formation of H₂O(g)?

• 1. It is exothermic, and heat is released.

• 1. It is exothermic, and heat is absorbed.

• 1. It is endothermic, and heat is released.

• 1. It is endothermic, and heat is absorbed.

According to Table I, which salt releases energy as it dissolves?

• 1. KNO₃

• 1. LiBr 

• 1. NH₄NO₃

• 1. NaCl

1)    Which statement describes the characteristics of an endothermic reaction?

• 1. The sign of ΔH is positive, and the products have less potential energy than the reactants.

• 1. The sign of ΔH is positive, and the products have more potential energy than the reactants.

• 1. The sign of ΔH is negative, and the products have less potential energy than the reactants.

• 1. The sign of ΔH is negative, and the products have more potential energy than the reactants.

Which statement correctly describes this reaction?

• 1. It is endothermic and energy is absorbed.

• 2. It is endothermic and energy is released.

• 1. It is exothermic and energy is absorbed.

• 1. It is exothermic and energy is released.

1)    Given the balanced equation representing a reaction: 

N₂(g) + O₂(g) + 182.6 kJ → 2NO(g)

Which potential energy diagram below correctly illustrates this reaction?

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1)    Which arrow represents the activation energy for the foward reaction?

• 1. A 

• 1. B

• 1. C

• D

1)    Assume that the potential energy of the products in a chemical reaction is 60 kilocalories. This reaction would be exothermic if the potential energy of the reactants were

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  1. 50 kcal

• 1. 20 kcal

• 1. 30 kcal

• 1. 80 kcal

1)    Chemical cold packs are often used to reduce swelling after an athletic injury. The diagram represents the potential energy changes when a cold pack is activated.  Which lettered interval on the diagram represents the heat of reaction?

• A

• B

• C

• D