Heat flow and the final temperature of a mixture

Answer Key - Grade 11 Science Worksheet

Circle the best answer, or write your answer on the line.

1. 1.

   In an insulated cup, 300 g of water goes from 20 °C to 32 °C. With c = 4182 J/(kg·°C), how much heat moves in or out, Ari?

   15,055.2 J
2. 2.

   In an insulated cup, 500 g of water goes from 90 °C to 70 °C. With c = 4182 J/(kg·°C), how much heat moves in or out, Bo?

   41,820 J
3. 3.

   In an insulated cup, 120 g of water goes from 15 °C to 40 °C. With c = 4182 J/(kg·°C), how much heat moves in or out, Esme?

   12,546 J

4. Read this first

   Specific heats (Engineering ToolBox)

   Material	Specific heat (J/(kg·°C))
   water	4182
   aluminum	897
   iron	449
   copper	385

5. 4.

   Using the table, about how many times as much heat does water need as copper for the same mass and warming, Kira?

   • About 11 times
   • About 4 times
   • About 2 times
6. 5.

   Using the table, how much heat warms 2 kg of iron by 10 °C, Luz?

   • 89,800 J
   • 898 J
   • 8980 J

7. Mixing water in a cup (example data)

   Trial	Hot water	Cold water	Lid	Predicted final (°C)	Measured final (°C)
   1	200 g at 70 °C	200 g at 20 °C	yes	45	44
   2	100 g at 80 °C	300 g at 20 °C	yes	35	34
   3	200 g at 70 °C	200 g at 20 °C	no	45	41

8. 6.

   Using the table, how was trial 2's predicted final temperature found, Milo?

   • (80 + 20) ÷ 2 = 50 °C
   • (100 × 80 + 300 × 20) ÷ 400 = 35 °C
   • 80 − 20 = 60 °C
9. 7.

   Using the table, why is each measured final temperature a little below the prediction, Noah?

   • The cold water gives off cold
   • Heat is destroyed when the two waters mix
   • Some heat escapes to the cup and the air
10. 8.

    In an insulated cup, hot water gives out 5000 J while warming some cold water. How much heat does the cold water gain, Ren?

    • 10,000 J
    • 5000 J
    • 2500 J
11. 9.

    A hot iron block goes into cool water in an insulated cup. What is true once nothing is changing, Tala?

    • They hold the same thermal energy
    • The block is still a little hotter
    • They are at the same temperature
12. 10.

    Why does a hot 0.5 kg aluminum block warm 1 kg of water by only a few degrees, Zee?

    • Water needs much more heat per degree
    • Aluminum can't give out heat
    • The block cools by the same number of degrees