Energetics

Worked examples (6)

• 1Find the heat energy Q (Getting started)
• 2ΔH of combustion from moles given (Getting started)
• 3ΔH of neutralisation (Building confidence)
• 4ΔH of dissolving — an endothermic case (Building confidence)
• 5ΔH of combustion of ethanol from mass burned (Stretch)
• 6ΔH of displacement — work back to ΔT (Stretch)

Model answers (6)

• ✓Model answer — 4WSD0/1C style
• ✓Model answer — 4WSD0/1C style
• ✓Model answer — 4WSD0/1C style
• ✓Model answer — 4WSD0/1C style
• ✓Model answer — 4WSD0/1C style — extended
• ✓Model answer — 4WSD0/1C style — extended

Worked examples (6)

• 1Classify reactions as exo or endo (Getting started)
• 2Use a temperature change to classify (Getting started)
• 3Label an energy level diagram (Building confidence)
• 4Explain the sign of ΔH using bonds (Building confidence)
• 5Interpret an endothermic profile (Stretch)
• 6Explain a hot displacement reaction (Stretch)

Model answers (6)

• ✓Model answer — 4WSD0/1C style
• ✓Model answer — 4WSD0/1C style
• ✓Model answer — 4WSD0/1C style
• ✓Model answer — 4WSD0/1C style
• ✓Model answer — 4WSD0/1C style — extended
• ✓Model answer — 4WSD0/1C style — extended

Worked examples (6)

• 1Choose the right calorimeter (Getting started)
• 2Exothermic or endothermic from the temperature change (Getting started)
• 3Describe the combustion calorimetry method (Building confidence)
• 4Variables to control when comparing fuels (Building confidence)
• 5Explain why the result is below the data-book value (Stretch)
• 6Classify and improve a displacement calorimetry experiment (Stretch)

Model answers (6)

• ✓Model answer — 4WSD0/1C style
• ✓Model answer — 4WSD0/1C style
• ✓Model answer — 4WSD0/1C style
• ✓Model answer — 4WSD0/1C style
• ✓Model answer — 4WSD0/1C style — extended
• ✓Model answer — 4WSD0/1C style — extended

Worked examples (6)

• 1A first Q = mcΔT calculation (Getting started)
• 2Convert cm³ of water to grams first (Getting started)
• 3Calculate Q then convert to kJ (Building confidence)
• 4Combustion: use the WATER mass, not the fuel mass (Building confidence)
• 5Rearrange to find the temperature change (Stretch)
• 6Two-step problem: convert units then calculate (Stretch)

Model answers (6)

• ✓Model answer — 4WSD0/1C style
• ✓Model answer — 4WSD0/1C style
• ✓Model answer — 4WSD0/1C style
• ✓Model answer — 4WSD0/1C style
• ✓Model answer — 4WSD0/1C style — extended
• ✓Model answer — 4WSD0/1C style — extended