Evaporating sweat cools the body because evaporation is an...

Evaporating sweat cools the body because evaporation is an endothermic process: $$ \mathrm{H}_{2} \mathrm{O}(l) \longrightarrow \mathrm{H}_{2} \mathrm{O}(g) \quad \Delta H_{\mathrm{ran}}^{\mathrm{o}}=+44.01 \mathrm{~kJ} $$ Estimate the mass of water that must evaporate from the skin to cool the body by $0.50^{\circ} \mathrm{C}$. Assume a body mass of $95 \mathrm{~kg}$ and assume that the specific heat capacity of the body is $4.0 \mathrm{~J} / \mathrm{g} \cdot{ }^{\circ} \mathrm{C}$.

Evaporating sweat cools the body because evaporation is an endothermic process:
$$
\mathrm{H}_{2} \mathrm{O}(l) \longrightarrow \mathrm{H}_{2} \mathrm{O}(g) \quad \Delta H_{\mathrm{ran}}^{\mathrm{o}}=+44.01 \mathrm{~kJ}
$$
Estimate the mass of water that must evaporate from the skin to cool the body by $0.50^{\circ} \mathrm{C}$. Assume a body mass of $95 \mathrm{~kg}$ and assume that the specific heat capacity of the body is $4.0 \mathrm{~J} / \mathrm{g} \cdot{ }^{\circ} \mathrm{C}$.

Key Concepts

Specific Heat Capacity

Specific heat capacity is the measure of how much energy is required to raise the temperature of a unit mass of a substance by one degree Celsius. It is an essential property in thermal processes, allowing calculations of energy changes when a substance undergoes a temperature change.

Latent Heat of Vaporization

Latent heat of vaporization is the energy needed to convert a unit mass of a liquid into vapor at a constant temperature. This concept is crucial when analyzing phase changes, where energy is absorbed without a change in temperature.

Heat Transfer and Energy Balance

Heat transfer and energy balance involve the principles of conserving energy and tracking its movement within a system. This includes calculating the energy required or removed to achieve a specific temperature change, thereby connecting material properties like specific heat capacity and latent heat.

Endothermic Processes

Endothermic processes are those that absorb energy from their surroundings, leading to a decrease in temperature. Understanding endothermic reactions is key in explaining phenomena like evaporation, where the absorption of heat results in cooling effects.

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