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Question 23 (3 points)

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Thermos, like the Yeti, are used to keep hot liquids hot and cold liquids cold. Below is a diagram of a thermos. The diagram shows how a thermos works.

Using the diagram and your knowledge of heat, which explanation is accurate about how the thermos works?

Question 23 options:

The reflective lining prevents heat loss by radiation, and the vacuum prevents heat loss by conduction.

The reflective lining prevents heat loss by conduction, and the vacuum prevents heat loss by radiation.

The reflective lining and the vacuum both prevent heat loss by conduction and radiation.

The reflective lining prevents heat loss by conduction and radiation, and the vacuum prevents heat loss by radiation only.

Question 24 (3 points)

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Refer to the data presented in the table below.

Substance

Specific heat (J/g°C)

Aluminum

0.90

Copper

0.39

Silver

0.23

Platinum

0.13

If 200 J of energy were added to each of these samples, which would experience the LEAST temperature increase?

Question 24 options:

Copper

Platinum

Aluminum

Silver

1 answer

Question 23

The correct explanation regarding how a thermos works is:

The reflective lining prevents heat loss by radiation, and the vacuum prevents heat loss by conduction.

Explanation: The reflective lining helps reflect thermal radiation back into the liquid, minimizing heat loss through radiation. The vacuum layer is an excellent insulator that prevents heat transfer via conduction (and convection) as there are no particles in a vacuum to transfer heat.

Question 24

To determine which substance experiences the least temperature increase when 200 J of energy is added, we can use the formula:

\[ \Delta T = \frac{Q}{m \cdot c} \]

Where:

  • \( \Delta T \) = change in temperature
  • \( Q \) = heat energy added (200 J)
  • \( m \) = mass of the sample (not provided, but will cancel out if we compare ratios)
  • \( c \) = specific heat capacity of the substance

Since we're comparing the temperature increases relative to their specific heat values, we can see that higher specific heat values result in lower temperature increases.

The specific heats are as follows:

  • Aluminum: 0.90 J/g°C
  • Copper: 0.39 J/g°C
  • Silver: 0.23 J/g°C
  • Platinum: 0.13 J/g°C

The substance with the lowest specific heat will experience the greatest temperature increase, and the one with the highest specific heat will experience the least temperature increase.

  1. Aluminum (0.90)
  2. Copper (0.39)
  3. Silver (0.23)
  4. Platinum (0.13)

Thus, Platinum, with the lowest specific heat, would experience the least temperature increase.

Correct Answer: Platinum