Heat flow and the final temperature of a mixture

Answer Key - Grade 11 Science Worksheet - Building Confidence

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

1. 1.

   In an insulated cup, 100 g of water at 85 °C mixes with 400 g of water at 25 °C. What final temperature do they reach, Bo?

   37 °C
2. 2.

   In an insulated cup, 400 g of water at 50 °C mixes with 100 g of water at 10 °C. What final temperature do they reach, Esme?

   42 °C

3. Read this first

   Use this

   Energy bar chart (example data), one bar per energy store, height in °C. Start: hot water 80 °C; cold water 20 °C. End: hot water 60 °C; cold water 60 °C. A transfer arrow goes from the hot water to the cold water, labeled heat 16,728 J. 200 g of water at 80 °C mixes with 100 g of water at 20 °C in an insulated cup. Bars show temperature.

4. 3.

   In the energy bar chart, which way does heat move, Jun?

   • Both ways equally, so nothing changes
   • From the hot water to the cold water
   • From the cold water to the hot water
5. 4.

   In the energy bar chart, when does the heat stop moving, Kira?

   • When both reach 60 °C
   • When both reach 50 °C, halfway
   • When the hot water reaches 20 °C
6. 5.

   In the energy bar chart, why is the final temperature closer to 80 °C than to 20 °C, Luz?

   • There is twice as much hot water
   • Hot water holds heat better than cold water
   • Heat moves faster than cold
7. 6.

   A metal spoon stands in hot cocoa. Why does its handle warm up, Noah?

   • Cold leaves the handle
   • The handle makes its own heat
   • Heat moves along the spoon from the hot end
8. 7.

   A cold drink sits in a warm room. When does it stop warming up, Pia?

   • After exactly one hour
   • When it reaches the room's temperature
   • When it is warmer than the room
9. 8.

   Water's specific heat is 4182 J/(kg·°C) and aluminum's is 897. Equal masses of each get the same heat. Which warms more, Ren?

   • They warm by the same amount
   • The water
   • The aluminum
10. 9.

    What does water's specific heat of 4182 J/(kg·°C) mean, Tala?

    • 4182 J warms 1 kg of water by 1 °C
    • 4182 J warms 1 g of water by 1 °C
    • 1 kg of water holds 4182 J in total
11. 10.

    Why does a lake cool more slowly at night than the dry sand beside it, Zee?

    • Water can't lose heat at night
    • Water's specific heat is much higher
    • Sand holds more heat per kilogram per degree