Enthalpy (Chapter 7)

What is enthalpy?

• Δ H: the change in heat energy
• Positive H: Heat energy lost in a reaction
• Negative H: Heat energy gained in a reaction

What is the formula for enthalpy?

• H of products minus H of reactants
• H of reactants minus heat of products
• H of activation energy
• H of reverse activation energy

If a reaction is exothermic, what is the sign for ΔH?

• Negative
• Positive

On the graph displayed, what is B? (middle tallest arrow)

• Activated Complex
• Activation Energy
• Delta H
• Potential Energy

If the potential energy of the reactants in a reaction is 75 and the potential energy of the products is 97, what is the ΔH?

• 22 kJ
• 22 kJ/mol
• 122 kJ/mol
• 122 kJ

When the enthalpy of a reaction is -30 kJ/mol, and the potential energy of the reactants is 50 kJ/mol, state exo- or endo-thermic and why.

• Endothermic because ΔH is negative
• Endothermic because potential energy of reactants is positive
• Exothermic because ΔH is negative
• Exothermic because potential energy of the reactants is more than that of the products

Define A and E on the diagram attached

• A) Activation Energy &
   E) Reverse Activation Energy
• A) ΔH &  E) Activation Energy
• A) Activation Energy &
  E) Falling Energy
• A) Reverse Activation Energy & E) Activation Energy

In an endothermic reaction, you are given 14 kJ/mol of reverse activation energy and 23 kJ/mol of ΔH. Find the activation energy?

• 37 kJ/mol
• 9 kJ/mol
• -9 kJ/mol

When given the equation 2C(s) + H₂(g) + 226.7 kJ/mol --> C₂H₂(g), calculate the new ΔH if 0.766g of O₂ are used.

• 86.13 kJ/mol
• 173.65 kJ/mol
• 350.08 kJ/mol
• 16.76 kJ/mol

When 2Na(s) + Cl₂(g) --> NaCl(s) + 822 kJ/mol is proceeded, what is the new ΔH when 36.25g of sodium is reacted?

• -1043 kJ/mol
• 648 kJ/mol
• -810.6 kJ/mol
• 1043 kJ/mol