ENERGY CHANGES

Is this equation endo- or exo-thermic?

PCl₃ (s) + Cl₂ (g) --> PCl₅ (s) + energy

• endothermic

• exothermic

Is this equation endo- or exo-thermic?

2KNO₃ (s) + energy --> 2KNO₂ (s) + O₂

• endothermic

• exothermic

When new chemical bonds form, energy ____________.

• is taken into the system.

• stays the same in the system.

• is released from the system.

When the solids Ba(OH)₂ and NH₄SCN are mixed, a solution is produced, and the temperature drops. Which statement about the energetics of this reaction is correct?

• The reaction is endothermic and ΔH is negative.

• The reaction is exothermic and ΔH is negative.

• The reaction is endothermic and ΔH is positive.

• .The reaction is exothermic and ΔH is positive.

Which of the following is TRUE about the bond-breaking process of the reactants?

• It absorbs energy.

• There's no energy involved.

• It releases energy.

What type of reaction is represented by the graph above?

• endothermic

• exothermic

What type of reaction is represented by the graph above?

• endothermic

• exothermic

Using the table of average bond energies at the bottom of the image, what is the ΔH in kJ for the reaction above.

• +160 kJ

• -160 kJ

• - 63 kJ

• - 217 kJ

The average bond enthalpies for O-O and O=O are 146 and 496 kJ/mol respectively. What is the enthalpy change, in kJ, for the reaction below?

H-O-O-H(g) → H-O-H(g) + ½O=O(g)

• -102 kJ

• - 350 kJ

• +102 kJ

• +350 kJ

Identify whether the reaction above is exothermic or endothermic. Use the table of bond energies found below the reaction. 

• endothermic

• exothermic