Question

Aluminum has a specific heat of 0.900 J/(g°C). How much energy in kJ is needed to raise the temperature of a 625 g block of aluminum from 30.7°C to 82.1°C?

Answer 1

About 28.9 kJ.

Step-by-step explanation:

Recall the formula for specific heat:

`\displaystyle q = mC\Delta T`

Where q is the amount of heat released, m is the mass of the substance, C is its specific heat, and ΔT is the change in temperature.

Therefore, by substitution, we have that:

`\displaystyle \begin{aligned} q & = (625\text{ g})\left(\frac{0.900 \text{ J}}{\text{g-$^\circ$C}}\right)\left(\frac{1 \text{ kJ}}{1000 \text{ J}}\right) \left(82.1^\circ\text{C}-30.7^\circ \text{C}\right) \\ \\ & = (625\text{ g})\left(\frac{0.900 \text{ J}}{\text{g-$^\circ$C}}\right)\left(\frac{1 \text{ kJ}}{1000 \text{ J}}\right)(51.4^\circ\text{C}) \\ \\ & = 28.9\text{ kJ}\end{aligned}`

In conclusion, about 28.9 kJ of energy is needed.