How the runs are made
Each run starts from a hidden true value (a metal’s specific heat, or ΔH for a reaction) and the masses on the sheet. The final temperature is worked out from the heat balance and drawn on a thermometer division, so the reading is exact and the answer comes out close to the true value, as in a real lab. Cooling-correction graphs add a steady drift toward room temperature and a slow start, so the highest reading is always at least two small squares short of the extrapolated one.
Example
In set HEAT2D (high school), a 68.9 g metal block at 80.0 °C goes into 125.0 g of water. Thermometer A reads 18.0 °C and B reads 21.0 °C, so the water gained q = 125.0 × 4.18 × 3.0 = 1,567.5 J. The metal cooled by 59.0 °C, so c = 1,567.5 ÷ (68.9 × 59.0) = 0.386 J/(g·°C), closest to copper (0.385). Open set HEAT2D
Which mass to use
For a solid dissolving, OpenStax and most US courses use the mass of the whole solution (water plus solid); AQA’s A-level practical handbook uses the water only. Each question says which one it uses, and a hint spots the other.
Questions
How do you calculate heat in a calorimetry experiment?
Find the temperature change of the water or solution, then q = m c ΔT. With c = 4.18 J/(g·°C) and 100.0 g of water warming by 5.0 °C, q = 2,090 J.
Why is q for the reaction the negative of q for the solution?
The heat the reaction gives out is the heat the solution takes in. If the solution warms, q(solution) is positive, so q(reaction) is negative and the reaction is exothermic.
How do you find ΔH per mole?
Divide −q(solution) by the moles that reacted or dissolved, and change J to kJ. A negative ΔH means exothermic, a positive one endothermic.
Why extrapolate back to the mixing time?
The reaction or dissolving takes time, and heat leaks to or from the room meanwhile. Carrying the straight line of later readings back to the mixing time gives the temperature change with no leak.
How do you identify a metal from its specific heat?
Work out c from the heat the water gained and the metal’s own temperature drop, then pick the closest value in a table: aluminum 0.897, iron 0.449, copper 0.385, lead 0.130 J/(g·°C).
What specific heat do you use for the solution?
Water’s: 4.18 J/(g·°C), or 4.18 J g⁻¹ K⁻¹ at A-level, with a density of 1.00 g/mL. GCSE physics uses 4200 J/kg °C.
Sources, checked October 25, 2026: College Board, AP Chemistry Course and Exam Description (PDF updated June 2026), topics 6.3 to 6.6; OpenStax Chemistry 2e, 5.1 Energy Basics (Table 5.1), 5.2 Calorimetry and 10.3 Phase Transitions (Flowers et al., Rice University, 2019, CC BY 4.0; specific heats of water and the metals and the enthalpies of water used here); AQA AS and A-level Chemistry specification, version 1.1 (December 1, 2015), 3.1.4; AQA A-level Chemistry practical handbook, version 2.1, required practical 2; AQA GCSE Chemistry 8462 specification, version 1.1 (October 4, 2019).