Question

The temperature of a 150.0 g sample of aluminum rises from 25°C to 40°C after it has been

placed on a hot plate. Calculate how much heat was transferred, and state whether it was
gained or lost based on the sign of your answer.
Q=
Gained or Lost:

PLEASE HELP!!!!

Answer 1

Q = 2.0 x 10³ J

Step-by-step explanation:

Using the change in temperature, we can find the heat transfer.

Heat Transfer

An increase in temperature is caused by absorbing energy. This means that the aluminum must have absorbed energy in order to rise in temperature. Since energy is being absorbed, the Q-value should be positive.

The equation for heat transfer is:

• Q = mcΔT

In this equation, Q is energy, m is mass, c is the specific heat, and ΔT is the change in temperature. Specific heat is a constant that every substance has that describes how much energy is needed to heat up the substance. These values can be found in a data table.

Solving for Q

To find Q, we can plug in the known values and solve. The question states that there are 150.0g of Al. The specific heat of Al is 0.897 J/g*C. Also, since 40-25 = 15, the change in temperature is +15°C.

• Q = 150.0 * 0.897 * 15
• Q ≈ 2018.25 J

Since this question is based on measured values, we need to round according to significant figures. Our answer should have 2 sig figs. This means the answer rounds down to 2000J; however, this only has 1 sig fig. So, we need to use scientific notation to write our answer.

Given that Q is positive, the aluminum gains 2.0 x 10³ J of energy.