Q: Which equation correctly represents the heat lost by the hot object and the heat gained by the cold object during thermal equilibrium?

$q_{\text{lost (Object)}} = q_{\text{gained (solvent)}}$

Q: If 53.2 g of Al at 120.0 $^ ext{o}$C is placed in 110.0 g H$_2$O at 90 $^ ext{o}$C in an insulated container, which equation would you use to find the final temperature ($T_f$) of the system?

$m_{\text{Al}} c_{\text{Al}} (T_f - T_{\text{Al,initial}}) + m_{\text{H}_2\text{O}} c_{\text{H}_2\text{O}} (T_f - T_{\text{H}_2\text{O,initial}}) = 0$

Question 1

Which of the following best describes thermal equilibrium?

Accepted Answer

When two substances in contact have the same temperature and no longer exchange heat.

Question 2

A 50 g block of lead at 250 $^	ext{o}$C is submerged in a solution at 90 $^	ext{o}$C. Under ideal thermal equilibrium, what will be the final temperature of the solution?

Accepted Answer

Greater than 90 $^	ext{o}$C

Question 3

Which equation correctly represents the heat lost by the hot object and the heat gained by the cold object during thermal equilibrium?

Accepted Answer

$q_{	ext{lost (Object)}} = q_{	ext{gained (solvent)}}$

Question 4

If 53.2 g of Al at 120.0 $^	ext{o}$C is placed in 110.0 g H$_2$O at 90 $^	ext{o}$C in an insulated container, which equation would you use to find the final temperature ($T_f$) of the system?

Accepted Answer

$m_{	ext{Al}} c_{	ext{Al}} (T_f - T_{	ext{Al,initial}}) + m_{	ext{H}_2	ext{O}} c_{	ext{H}_2	ext{O}} (T_f - T_{	ext{H}_2	ext{O,initial}}) = 0$

Question 5

Given the specific heat capacities $c_{	ext{Al}} = 0.897$ J/g$	ext{ }^	ext{o}$C and $c_{	ext{H}_2	ext{O}} = 4.184$ J/g$	ext{ }^	ext{o}$C, which substance will experience the greatest temperature change when the same amount of heat is absorbed?

Accepted Answer

Aluminum

Question 6

Why does heat transfer stop when thermal equilibrium is reached?

Accepted Answer

Because both objects have the same temperature.

Question 7

A student mixes 100 g of water at 80 $^	ext{o}$C with 100 g of water at 20 $^	ext{o}$C. What is the final temperature of the mixture, assuming no heat loss to the surroundings?

Accepted Answer

50 $^	ext{o}$C

Question 8

Which of the following statements is true about heat transfer in an insulated container?

Accepted Answer

Heat is only transferred between the substances inside the container.

Question 9

If the final temperature of a mixture is lower than the initial temperature of both substances, which of the following is most likely true?

Accepted Answer

Heat was lost to the surroundings.

Question 10

Which formula is used to calculate the amount of heat ($q$) absorbed or released by a substance?

Accepted Answer

$q = m c \Delta T$

Question 11

A metal block is heated and then placed in water. Which factor will NOT affect the final temperature of the water?

Accepted Answer

The color of the metal block.

Question 12

If two substances with different masses and specific heat capacities are mixed, which will reach a temperature closer to its initial temperature after equilibrium?

Accepted Answer

The substance with the larger mass and higher specific heat capacity.

Question 13

Which of the following is a real-world example of thermal equilibrium?

Accepted Answer

A cup of hot coffee cooling down to room temperature.

Question 14

If the heat capacity of a substance is very high, what does this imply about its temperature change when heat is added?

Accepted Answer

Its temperature will change very little.

Question 15

Which of the following best explains why metals feel colder than wood at the same temperature?

Accepted Answer

Metals conduct heat away from your skin more efficiently.

Thermal Equilibrium in GOB Chemistry: Concepts and Applications

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