Assessment: Energy Changes in Chemical Reactions

What does a negative ΔH indicate about a reaction?

What key property of enthalpy makes Hess's law true?

A reaction raises the temperature of 200 g of water by 5.0°C. How much heat (in J) was released? (c = 4.18 J/(g·°C))

A reaction's reactants have a total enthalpy of 210 kJ/mol; its products have 340 kJ/mol. Find ΔH (in kJ/mol).

Given N₂(g) + O₂(g) → 2NO(g), ΔH₁ = +180.5 kJ/mol, and 2NO(g) + O₂(g) → 2NO₂(g), ΔH₂ = −114.1 kJ/mol, find ΔH (in kJ/mol) for N₂(g) + 2O₂(g) → 2NO₂(g).

On an enthalpy diagram for an exothermic reaction, where should the products be drawn relative to the reactants, and why?

Two labs in different countries, at different temperatures and altitudes, both want to report the enthalpy of combustion of ethanol so the values can be compared. What must they do?

When combining two known reactions using Hess's law, one of them must be reversed to make the target equation work out. What must you do to that reaction's ΔH?