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Heat capacity and specific heat describe how materials absorb or release thermal energy when their temperature changes. Students need this reference to connect heat transfer equations with real laboratory measurements. It is especially useful for calorimetry, heating and cooling problems, and comparing how different substances respond to energy input. The central equation is q=mcΔTq = mc\Delta T, where heat depends on mass, specific heat, and temperature change. Heat capacity uses C=qΔTC = \frac{q}{\Delta T}, while specific heat uses c=qmΔTc = \frac{q}{m\Delta T}. In an insulated calorimeter, energy conservation is often written as qlost+qgained=0q_{\text{lost}} + q_{\text{gained}} = 0.

Key Facts

  • Heat transferred during a temperature change is calculated with q=mcΔTq = mc\Delta T.
  • Temperature change is found using ΔT=TfTi\Delta T = T_f - T_i.
  • Specific heat capacity is calculated with c=qmΔTc = \frac{q}{m\Delta T} and has units of J/(kgK)\text{J/(kg}\cdot\text{K)} or J/(gC)\text{J/(g}\cdot{}^{\circ}\text{C)}.
  • Heat capacity is calculated with C=qΔTC = \frac{q}{\Delta T} and has units of J/K\text{J/K} or J/C\text{J/}^{\circ}\text{C}.
  • For the same heat input, a larger specific heat means a smaller temperature change because ΔT=qmc\Delta T = \frac{q}{mc}.
  • In an insulated system, conservation of energy gives qlost+qgained=0q_{\text{lost}} + q_{\text{gained}} = 0.
  • A positive value of qq means the object gains thermal energy, while a negative value of qq means it loses thermal energy.
  • Temperature changes in kelvins and degrees Celsius have the same size, so ΔT=1K\Delta T = 1\,\text{K} is equivalent to ΔT=1C\Delta T = 1\,{}^{\circ}\text{C}.

Vocabulary

Heat
Heat is thermal energy transferred between objects because of a temperature difference.
Temperature
Temperature is a measure related to the average kinetic energy of particles in a substance.
Specific heat capacity
Specific heat capacity is the energy needed to raise the temperature of 1kg1\,\text{kg} or 1g1\,\text{g} of a substance by 1K1\,\text{K} or 1C1\,{}^{\circ}\text{C}.
Heat capacity
Heat capacity is the energy needed to raise the temperature of an entire object by 1K1\,\text{K} or 1C1\,{}^{\circ}\text{C}.
Calorimetry
Calorimetry is the measurement of heat transfer using temperature changes in a controlled system.
Thermal equilibrium
Thermal equilibrium occurs when objects in contact reach the same temperature and no net heat flows between them.

Common Mistakes to Avoid

  • Using TiTfT_i - T_f instead of ΔT=TfTi\Delta T = T_f - T_i is wrong because it reverses the sign of heat gained or lost.
  • Confusing heat capacity CC with specific heat cc is wrong because CC applies to a whole object, while cc applies per unit mass.
  • Mixing grams with J/(kgK)\text{J/(kg}\cdot\text{K)} is wrong because the mass unit must match the unit used for specific heat.
  • Forgetting that the hotter object has q<0q < 0 is wrong because it loses thermal energy as it cools.
  • Assuming all substances heat at the same rate is wrong because different materials have different specific heats.

Practice Questions

  1. 1 How much heat is required to raise the temperature of 0.50kg0.50\,\text{kg} of water from 20C20\,{}^{\circ}\text{C} to 80C80\,{}^{\circ}\text{C} if c=4186J/(kgK)c = 4186\,\text{J/(kg}\cdot\text{K)}?
  2. 2 A 200g200\,\text{g} metal sample absorbs 1500J1500\,\text{J} of heat and warms from 25C25\,{}^{\circ}\text{C} to 40C40\,{}^{\circ}\text{C}. What is its specific heat in J/(gC)\text{J/(g}\cdot{}^{\circ}\text{C)}?
  3. 3 An object has heat capacity C=750J/KC = 750\,\text{J/K}. What temperature change occurs when it absorbs 3000J3000\,\text{J} of heat?
  4. 4 Two equal-mass samples absorb the same amount of heat, but sample A has a larger specific heat than sample B. Which sample has the smaller temperature increase, and why?