WorksheetsBond Energy Calculations
Total questions: 10
Worksheet time: 12mins
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
The following equation shows the formation of magnesium oxide from magnesium metal. Which statement is correct for this reaction?
2Mg(s) + O2(g) → 2MgO(s) ΔH = -1204 kJ
1204 kJ of energy are released for every mole of magnesium reacted
602 kJ of energy are absorbed for every mole of magnesium oxide formed
602 kJ of energy are released for every mole of oxygen reacted
1204 kJ of energy are released for every two moles of magnesium oxide formed
For the reaction 2H2(g) + O2(g) → 2H2O(g) the bond enthalpies (in kJ/mol) are
H-H = x, O=O = y, O-H = z
Which calculation will give the value, in kJ/mol, of ΔH for the reaction?
2x + y - 2z
4z - 2x - y
2x + y - 4z
2z - 2x - y
Using the table of average bond energies below the image, the ΔH for the reaction in kJ is.....
+ 160 kJ
-63 kJ
- 160 kJ
-217 kJ
Does breaking bonds require energy, release energy, or not involve energy at all?
requires energy to break
releases energy when broken
No energy involved
What kind of energy change happens in the photosynthesis reaction in plant leaves?
Endothermic
Exothermic
No change
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
How can we figure out if an overall reaction is endo- or exo-thermic? It is the difference between _______ and __________.
hot and cold temperatures
energy to break and energy to form bonds.
time to form a bond versus time to break a bond
