IB Energetics

What do we mean by the term "standard conditions"?

• 1atm, 20C and 1moldm³

• 1atm, 0K and 1moldm³

• 10atm, 273K and 10mol/dm³

• 100kPa, 298K and 1mol/dm³

Define Endothermic by picking the correct statements

• ΔH is positive

• Energy is taken in from the surroundings (temperature goes down).

• Energy is given out to the surroundings (temperature goes up).

• · Products have less energy than the reactants

• products have more energy than the reactants

Define the term Exothermic by picking the correct statements

• Products have less energy than the reactants

• ΔH is negative

• ΔH is positive

• Energy is given out to the surroundings (temperature goes up).

• products have more energy than the reactants

Match the definition to the correct term.

The enthalpy change that accompanies a reaction in the molar quantities shown in a chemical reaction under standard conditions with all reactants and products in their standard states.

• The enthalpy of formation

• The enthalpy of reaction

• The enthalpy of combustion

• The enthalpy of neutralisation

Match the definition below to the correct term.

The enthalpy change that takes place when one mole of a substance is formed from its elements under standard conditions, with all species in their standard states.

• The enthalpy of neutralisation

• The enthalpy of combustion

• The enthalpy of formation

• The enthalpy of reaction

The enthalpy change when one mole of covalent bonds in a gaseous molecule is broken under standard conditions

• Bond enthalpy

• Enthalpy of atomisation

• Enthalpy of lattice dissociation

• Entropy (ΔS°)

Which change of state is exothermic? 

• CO₂(s) → CO₂(g)

• H₂O(l) → H₂O(g) 

• NH₃(g) → NH₃(l) 

• Fe(s) → Fe(l)

Which of the following enthalpy changes represent the enthalpy change of formation?

• Mg(s) + Cl₂(g) → MgCl₂(s)

• Mg²⁺(g) + 2 Cl ^-(g) → MgCl₂(aq)

• O2(g) → 2 O(g)

• 2Mg (s) + O₂(g) → 2MgO(S)

Which of the following equations represents the enthalpy change of combustion?

• 2C₄H₁₀(g) +13O₂(g) → 8CO₂ (g) + 10H₂0(g)

• C₄H₁₀(g) +13/2O₂(g) → 4CO₂ (g) + 5H₂0(g)

• C₄H₁₀ + 9/2O₂ = 4CO (s)+ 5H₂O

• C₄H₁₀ + 5/2O₂ = 4C(s) + 5H₂O(g)

Which of the following represent the enthalpy change of atomisation?

• O₂(g) → 2 O(g)

• Mg(s) → Mg(g)

• Mg(s) + Cl₂(g) → MgCl₂(s)

• Ca(g) → Ca²⁺(g) + 2 e