Question

Can someone just show me how to do this please?

As 390 g of hot milk cools in a mug, it transfers 30,000 J of heat to the environment. What is the temperature change of the milk? The specific heat of milk is 3.9 J/g·°C.

Answer 1

heat transferred q, is\[q=mc \Delta T\]you have m=390, q=30,000, c=3.9. Plu in your values and solve for delta T.

Answer 2

390 x 30,000 x 3.9 = 45,630,000 ?

Answer 3

\[\Delta T= \frac{q}{mc}\]try it again

Answer 4

I'm confused about the symbols

Answer 5

ok. delta T is the change in temperature. This is what you are asked to solve for. q is the quantity of heat transferred. m=the mass of the sample. and c is the specific heat capacity of the substance.

Answer 6

m = 390 right?

Answer 7

yes

Answer 8

q = 30,000 and c = 3.9 then?

Answer 9

you have to be a bit careful with q, the quantity of heat transferred. When heat leaves your sample q is negative. When heat enters your sample q is a positive quantity.

Answer 10

so in this case, it's negative?

Answer 11

yep. so we expect the temperature to decrease, since it is cooling off after all.

Answer 12

Ohh okay... so how do I write the equation?

Answer 13

I already gave you the equation. all you have to do is put in the numbers and solve.

Answer 14

\[30,000 \div 390 x 3.9\]?

Answer 15

yeah.\[\Delta T=\frac{30000}{(390)(3.9)}\]

Answer 16

well, should be -30000/(390*3.9) but yeah

Answer 17

-0.0507 ?

Answer 18

no. make sure you use brackets around the denominator in your calculator

Answer 19

-19.72 ?

Answer 20

you should get -19.7 degrees. So the milk's temperature decrease by 19.7 degrees C

Answer 21

thank you so much

Answer 22

no problem :)