Question

in a lab experiment to test the change in temperature of NaCl and the change in temperature of water:

Specific heat of NaCl is 0.88
specific heat of DI water is 4.2

in the experiment, the change in temperature for the water was much greater than the change in temperature of the table salt as well as the change in energy.
(when using equation E = g C × change in T)

why did this occur?

Answer 1

The question is a bit unclear to me. Do you want to know why water will have a higher energy change or why water will have a lower temperature change?

I will answer both.

The heat absorbed or released by a substance is given by ΔH = m*C*Δt where m is the mass of the substance, C is the specific heat capacity and Δt is the change in temperature.

C for salt = 0.88 J/g.°C

C for water = 4.2 J/g.°C

Case 1: Suppose we have the same mass of both salt and water (say 10.0 g) and we have the same temperature change (say 10.0°C).

ΔH (salt) = (10.0 g)*(0.88 J/g.°C)*(10.0 °C) = 88 J

ΔH (water) = (10.0 g)*(4.2 J/g.°C)*(10.0 °C) = 420 J

Clearly, water will have a much higher energy change (heat change), almost 4 times as high as salt. This is because of the specific heat capacity of water is much higher than the specific heat capacity of salt. Specific heat capacity of water is 4.2 J/g.°C is the amount of energy required to raise the temperature of 1 g of water by 1 °C.

Case 2: Suppose we have the same mass of both salt and water (again 10.0 g say) and the same energy change (say 100 J) for both.

Use the same expression as before, but this time we want to find out the change in temperature.

Δt = ΔH/(m.C)

Δt (salt) = (100 J)/(10.0 g)(0.88 J/g.°C) = 11.36 °C

Δt (water) = (100 J)/(10.0 g)(4.2 J/g.°C) = 2.38 °C

For the same amount of energy absorbed by the same amount of both salt and water, salt will have a much higher temperature change than water. The reason is again the same. The specific heat capacity of water being much higher than that of salt, water must expend a large amount of energy to bring about the same temperature change as salt.