1.
How many joules of heat is required to heat 68.00 grams of aluminum foil from 55.00 °C to 93.00 °C in case aluminum has a specific heat of 0.90 J/g °C?
Correct Answer
A. 2326 J
Explanation
The amount of heat required to heat a substance can be calculated using the formula Q = m * c * ΔT, where Q is the heat energy, m is the mass of the substance, c is the specific heat capacity, and ΔT is the change in temperature. In this case, the mass of aluminum foil is 68.00 grams, the specific heat capacity is 0.90 J/g °C, and the change in temperature is (93.00 - 55.00) °C = 38.00 °C. Plugging these values into the formula, we get Q = 68.00 * 0.90 * 38.00 = 2326 J.
2.
What is the final temperature of a 91.0 g piece of copper, with an initial temperature of 20.0 °C, after absorbing 1581 J of heat? Copper has a specific heat of 0.386 J/g °C.
Correct Answer
A. 65.0 °C
Explanation
The final temperature of the copper can be calculated using the formula: q = m * c * ΔT, where q is the amount of heat absorbed, m is the mass of the copper, c is the specific heat of copper, and ΔT is the change in temperature. Rearranging the formula to solve for ΔT, we have ΔT = q / (m * c). Plugging in the given values, we get ΔT = 1581 J / (91.0 g * 0.386 J/g °C) = 4.73 °C. Adding this change in temperature to the initial temperature of 20.0 °C, we get the final temperature of 65.0 °C.
3.
What is the specific heat of gold if a 38.0-gram bracelet releases 460.8 Joules of heat energy and the increase in temperature is 94.0 °C?
Correct Answer
A. 0.129 J/g °C
Explanation
The specific heat of a substance is the amount of heat energy required to raise the temperature of 1 gram of the substance by 1 degree Celsius. In this question, we are given the mass of the gold bracelet (38.0 grams), the amount of heat energy released (460.8 Joules), and the increase in temperature (94.0 °C). To find the specific heat, we can use the formula Q = mcΔT, where Q is the heat energy, m is the mass, c is the specific heat, and ΔT is the change in temperature. Rearranging the formula to solve for c, we have c = Q / (mΔT). Plugging in the given values, we get c = 460.8 J / (38.0 g * 94.0 °C) = 0.129 J/g °C.
4.
The temperature of an element affects its weight.
Correct Answer
A. True
Explanation
The statement is true because temperature can affect the weight of an element due to thermal expansion or contraction. When an element is heated, its particles gain energy and move more rapidly, causing the element to expand and therefore increase in weight. Conversely, when an element is cooled, its particles lose energy and move more slowly, causing the element to contract and decrease in weight. Therefore, temperature does have an impact on the weight of an element.
5.
202.8 J of heat is released from a piece of silver while cooling 65.0 °C. What's the mass of the sample? Silver has a specific heat of 0.240 J/g °C.
Correct Answer
A. 13.0 grams
Explanation
The specific heat of silver is given as 0.240 J/g °C. We know that the heat released is 202.8 J and the temperature change is 65.0 °C. Using the formula Q = mcΔT, where Q is the heat released, m is the mass, c is the specific heat, and ΔT is the temperature change, we can rearrange the formula to solve for mass. Plugging in the given values, we get 202.8 J = m * 0.240 J/g °C * 65.0 °C. Solving for m, we find that the mass of the sample is 13.0 grams.
6.
250.8 J of heat is released from a piece of gold while cooling 65.0 °C. 13.0 grams is the mass of the sample. Gold has a specific heat of 0.240 J/g °C.
Correct Answer
B. False
Explanation
The statement is false because the given information does not match the correct calculation. The correct calculation would be to multiply the mass of the sample (13.0 g) by the specific heat of gold (0.240 J/g °C) and the change in temperature (65.0 °C). This would give us the amount of heat released, which should be equal to 249.6 J. Since the given value is 250.8 J, it does not match the correct calculation and therefore the statement is false.
7.
3780.8 J of heat is released from a piece of gold while cooling 25.0 °C. 11.0 grams is the mass of the sample. Gold has a specific heat of 0.670 J/g °C.
Correct Answer
B. False
Explanation
The statement is false because the given information does not match the correct calculation. According to the specific heat formula, the heat released can be calculated by multiplying the mass, temperature change, and specific heat. In this case, the heat released should be calculated as (11.0 g) x (25.0 °C) x (0.670 J/g °C) = 186.75 J, not 3780.8 J. Therefore, the given statement is false.
8.
Which is the definition of calorimetry?
Correct Answer
A. The science of calculating the heat of chemical reactions and physical changes
Explanation
Calorimetry is the science of calculating the heat of chemical reactions and physical changes. It involves measuring the amount of heat energy exchanged between a system and its surroundings. This can be done through various techniques, such as using a calorimeter to measure temperature changes or determining heat capacities. Calorimetry is important in understanding the energy changes that occur during chemical reactions and in studying the properties of substances.
9.
350.8 J of heat is released from a piece of silver while cooling 55.0 °C. 11.0 grams is the mass of the sample. Silver has a specific heat of 0.6220 J/g °C.
Correct Answer
B. False
Explanation
The statement is false because the given information does not match the correct formula for calculating heat transfer. The correct formula is Q = mcΔT, where Q is the heat transfer, m is the mass, c is the specific heat, and ΔT is the change in temperature. In this case, the heat transfer would be calculated as Q = (11.0 g)(0.6220 J/g °C)(55.0 °C) = 377.71 J, which is not equal to 350.8 J. Therefore, the statement is false.
10.
What is the change in temperature if a 70.0-gram sample of nickel absorbs 1756 J of energy? Nickel has a specific heat of 0.440 J/g °C.
Correct Answer
A. 57.0 °C
Explanation
The change in temperature can be calculated using the formula: q = m * c * ΔT, where q is the energy absorbed, m is the mass, c is the specific heat, and ΔT is the change in temperature. Rearranging the formula to solve for ΔT, we have ΔT = q / (m * c). Plugging in the given values, ΔT = 1756 J / (70.0 g * 0.440 J/g °C) = 57.0 °C. Therefore, the change in temperature is 57.0 °C.