Bond Energy

If the energy required to break the bonds is greater than the energy given out by making new bonds the reaction is....

• endothermic

• exothermic

• neutralisation

• combustion

If the energy required to break the bonds is less than the energy given out by making new bonds the reaction is

• endothermic

• exothermic

In an endothermic reaction the system is releasing energy.

• true

• false

In an exothermic reaction, energy is

• absorbed from the surrounding area

• created proportional to the change in mass

• stored in chemical bonds

• released into the surrounding area

How much energy would be needed to separate this atom?

C-H Bond Energy: 413 kJ/mol

• 413 kJ/mol

• 826 kJ/mol

• 1239 kJ/mol

• 1652 kJ/mol

Answer explanation

There are 4 C-H bonds so you need to multiply the bond energy for C-H 4 times

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.

• is released from the system.

• stays the same in 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 endothermic and ΔH is positive

• The reaction is exothermic and ΔH is negative

• The reaction is exothermic and ΔH is positive

ΔH value in an endothermic reaction is a positive number.

• True
• False