Final answer:
Heat transfer between two substances at different temperatures tends to flow from the warmer to the cooler until they reach thermal equilibrium. The rate and effect of heat transfer depend on temperature differences, masses, and specific heat capacities of the substances.
Step-by-step explanation:
When substances A and B with different temperatures are brought into contact, heat transfer occurs from the warmer substance to the cooler one. This process will continue until thermal equilibrium is reached, meaning both substances attain the same temperature. The rate of this energy flow depends on factors such as the temperature difference, the mass of the substances, and their thermodynamic properties like specific heat capacity.
Substance H with high temperature has atoms and molecules with higher average kinetic energy (KE) compared to substance L, which is cooler. Contact between H and L will result in heat transfer from H to L, reducing the temperature of H and increasing the temperature of L.
This will also correspond to changes in the average KE of the molecules in both substances. This energy exchange continues until the temperature of H and L equalize, stopping the net heat flow.
Calculating the final temperature after a heat transfer involves knowledge of the initial temperatures, the mass of the substances, and their respective specific heat capacities. For example, different temperature changes will occur when the same amount of heat is applied to equal masses of water, concrete, steel, and mercury, each initially at 20.0°C.