Need help with an Chemistry question

Question

What is the energy change when the temperature of 14.2 grams of solid copper is decreased from 39.1 °C to 20.5 °C .

what do I do first ? I have to teach myself cause of the virus

Answer 1

energy = heat = q = mass (m) x specific heat (C) x change in temperature (∆T).

So, this is the equation you want to use: q = mC∆T

q = ? This is what they are asking for, ie heat

m = mass = 14.2 grams

C = specific heat for copper. Usually given in the problem, but you can look it up. I found C = 0.386 J/g/ºC

∆T = change in temperature = 39.1º - 20.5º = 18.6ºC (NOTE: the temperature of the Cu DECREASED)

Plug in these numbers and solve for q:

q = (14.2 g)(0.386 J/g/ºC)(18.6ºC) = 101.95 J = - 102 J (NOTE the negative sign indicating an exothermic reaction since heat was given off by or lost from the Cu, i.e. temperature decreased. Also not the answer is reported to 3 significant figures)