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, 1 kg of each material gets 4182 J of heat. Which warms by only 1 °C, Jun?

   • Water
   • Aluminum
   • Copper
6. 5.

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

   • About 4 times
   • About 11 times
   • About 2 times
7. 6.

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

   • 898 J
   • 89,800 J
   • 8980 J

8. 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

9. 7.

   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
10. 8.

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

    • Some heat escapes to the cup and the air
    • The cold water gives off cold
    • Heat is destroyed when the two waters mix
11. 9.

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

    • 2500 J
    • 10,000 J
    • 5000 J
12. 10.

    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
    • They are at the same temperature
    • The block is still a little hotter