Thermochemistry Review

Which graph shows an exothermic reaction that produces 550 kJ of heat?

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Which statement is true?

• Endothermic reactions have a negative value of ∆H.

• An exothermic reaction transfers heat to the surroundings.

• Heat is given off when an endothermic reaction occurs

• The reaction vessel cools when an exothermic reaction occurs

Which is true for an exothermic reaction?

• The ∆H is positive

• The products have less potential energy than the reactants.

• The reactants have more kinetic energy than the products

• The reactants are below the products in potential energy

Is this reaction endothermic or exothermic, and is the value of ∆Hº positive or negative?

• endothermic, positive

• endothermic, negative

• exothermic, positive

• exothermic, negative

If heat is released by a chemical system, an equal amount of heat will be ____

• absorbed by the surroundings

• absorbed by the universe

• released by the surroundings

• released by the universe

Two blocks at different temp. are next to each other, heat will flow from block A to block B if

• Block A is 25° C and Block B is 25° C

• Block A is 15° C and Block B is 25° C

• Block A is 25° C and Block B is 15° C

• Block A is 0° C and Block B is 100° C

Solve the problem.

• 20.900 J

• 376.2 J

• 48,070

• 27,170 J

Calculate the enthalpy for the reaction: 4 NH₃(g) + 7 O₂(g) ---> 4 NO₂(g) + 6H₂O(g)

• -320.83 kJ

• 1,134.58 kJ

• -1,134.58 kJ

• The limit does not exist