Higher Chemistry - Unit 3 - Chemical Energy

Bond making and bond breaking. Which of following is TRUE?

• During bond breaking, heat is absorbed
• During bond making, heat is absorbed
• During bond breaking, heat is released
• None of the above

Tags

NGSS.HS-PS1-4

Which statement is FALSE for an endothermic reaction?

• Products higher in energy and less stable
• Reactants lower in energy and more stable
• Products have stronger bonds than reactants
• Reactants have stronger bonds than products

Tags

NGSS.HS-PS1-4

Which statement is FALSE for an exothermic reaction?

• Reactants higher in energy and less stable
• Product lower in energy and more stable
• Products have stronger bonds than reactants
• Reactants have stronger bonds than products

Tags

NGSS.HS-PS1-4

Which statements about exothermic reactions are correct?

I. They have negative ΔH values II. The products have a lower enthalpy than the reactants III. The products are more energetically stable than the reactants

• I and II only

• I and III only

• II and III only

• I, II, and III

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

• +102

• +350

• +394

Tags

NGSS.HS-PS1-4

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

Tags

NGSS.HS-PS1-4

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

Tags

NGSS.HS-PS1-4