Thermochemistry
q = mcΔT converts a temperature change into heat: mass times specific heat times the temperature change, with the sign doing the accounting (endothermic absorbs heat, exothermic releases it).
Solve each problem below; calculations are accepted within ±1%.
Common Questions
What is the difference between endothermic and exothermic?
Exothermic reactions release heat to the surroundings (negative enthalpy change, ΔH < 0). Endothermic reactions absorb heat from the surroundings (positive enthalpy change, ΔH > 0).
What is the specific heat capacity formula?
q = mcΔT, where q is heat (in joules), m is mass (in grams), c is specific heat capacity (J/g·°C), and ΔT is the change in temperature. Water has a specific heat of 4.184 J/g·°C.
What is calorimetry?
Calorimetry is the measurement of heat changes in chemical reactions or physical processes. A calorimeter measures the temperature change of a known mass of water (or solution) to calculate the heat released or absorbed.
What is Hess's Law?
Hess's Law states that the total enthalpy change of a reaction is the same regardless of the number of steps. You can add the ΔH values of individual steps to find the overall ΔH, even if the reaction doesn't actually occur in those steps.