Thermochemical Equations — Quiz

Question 1

Which statement is true for most chemical reactions?

Revolt · Accepted Answer

Energy is released during the formation of reactants.; An energy change occurs during the breaking and forming of bonds.

Question 2

Manganese dioxide MnO sub 2 times s , Δ⁢H_f=−520.0kJ reacts with aluminum to form aluminum oxide Al sub 2 cap o sub 3 s , Δ⁢H_f=−1699.8kJ and manganese according to the equation. 3 MnO sub 2 s plus 4 Al s rightarrow 2 Al sub 2 cap o sub 3 g plus 3 Mn s What is the enthalpy of the reaction? Use Δ⁢H_rxn=∑(Δ⁢H_f_1p⁢r⁢o⁢d⁢u⁢c⁢t⁢s)−∑(Δ⁢H_f_1r⁢e⁢a⁢c⁢tan⁡t⁢s)

Revolt · Accepted Answer

negative 1 comma 839 point 6 kJ

Question 3

Sulfur reacts with oxygen to form sulfur dioxide SO sub 2 times g , Δ⁢H_f=−296.8kJ/mol ) according to the equation. cap s times s plus cap o sub 2 times g rightarrow SO sub 2 times g What is the enthalpy change for the reaction? Use Δ⁢H_rxn=∑(Δ⁢H_f_1p⁢r⁢o⁢d⁢u⁢c⁢t⁢s)−∑(Δ⁢H_f_1r⁢e⁢a⁢c⁢tan⁡t⁢s)

Revolt · Accepted Answer

negative 296 point 8 kJ

Question 4

Which graph represents an exothermic reaction?

Revolt · Accepted Answer

Image with description A graph has Reaction progression on the horizontal axis and energy on the vertical axis. A line starts about halfway up the vertical axis and travels a short distance parallel to the horizontal axis; this segment is A plus B. The line then curves up sharply, peaks, and falls sharply to run parallel to and near the horizontal axis; the final segment is C. A double-headed arrow extends from A plus B to C.

Question 5

How is enthalpy used to predict whether a reaction is endothermic or exothermic?

Revolt · Accepted Answer

When the enthalpy change of the reaction is positive, the reaction is endothermic.

Question 6

Hydrogen reacts with chlorine to form hydrogen chloride HCl times g , Δ⁢H_f=−92.3kJ/mol according to the reaction. cap h sub 2 of g plus Cl sub 2 times g rightarrow 2 HCl g Which statement is correct? Use Δ⁢H_rxn=∑(Δ⁢H_f_1p⁢r⁢o⁢d⁢u⁢c⁢t⁢s)−∑(Δ⁢H_f_1r⁢e⁢a⁢c⁢tan⁡t⁢s)

Revolt · Accepted Answer

The enthalpy of the reaction is negative 184 point 6 kJ , and the reaction is exothermic.

Question 7

Which statement is true if the Δ⁢H_rxn of a reaction is positive?

Revolt · Accepted Answer

The reaction is endothermic.

Question 8

The Δ⁢H_rxn of formation of carbon dioxide is negative. Which statement is true?

Revolt · Accepted Answer

The reaction is exothermic.

Question 9

The enthalpy of formation for cap c sub 6 cap h sub 6 l is 49 point 0 kJ over mol Consider the reaction. 6 cap c open paren s comma graphite close paren plus 3 cap h sub 2 g rightarrow cap c sub 6 cap h sub 6 l Is the reaction endothermic or exothermic, and what is the enthalpy of reaction? Use Δ⁢H_rxn=∑(Δ⁢H_f_1p⁢r⁢o⁢d⁢u⁢c⁢t⁢s)−∑(Δ⁢H_f_1r⁢e⁢a⁢c⁢tan⁡t⁢s)

Revolt · Accepted Answer

endothermic; Δ⁢Hrxn=49.0 kJ

Thermochemical Equations — Quiz Answers

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