Question 1

What is enthalpy?

Accepted Answer

Enthalpy (H) is the total heat content of a system. Enthalpy change (ΔH) measures heat absorbed or released during a reaction at constant pressure. Negative ΔH means exothermic (releases heat); positive means endothermic (absorbs heat).

Question 2

What is the formula q = mcΔT?

Accepted Answer

q = mcΔT relates heat (q) to mass (m), specific heat capacity (c), and temperature change (ΔT = T_final - T_initial). It is used in calorimetry to measure heat changes in reactions.

Question 3

What is the specific heat of water?

Accepted Answer

The specific heat of liquid water is 4.184 J/(g·°C). This is relatively high, which is why water is commonly used as a calorimeter solvent and why it takes a lot of energy to heat water.

Question 4

How do I convert q to ΔH?

Accepted Answer

ΔH (per mole) = q / moles of reactant. Make sure to convert joules to kilojoules (divide by 1000) since ΔH is typically reported in kJ/mol. The sign indicates direction: negative for exothermic, positive for endothermic.

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