Question 1

Exactly 149.6 J will raise the temperature of 10.0 g of a metal from 25.0 °C to 60.0 °C. What is the specific heat capacity of the metal?

Accepted Answer

The specific heat capacity (c) is given by: 
c = Q/(mΔT) 
where Q is the amount of heat absorbed or released, m is the mass of the substance, and ΔT is the change in temperature. Substituting the given values: 
c = 149.6 J/(10.0 g x (60.0 °C - 25.0 °C)) 
c = 0.427 J/(g · °C) 
Therefore, the specific heat capacity of the metal is 0.427 J/(g · °C) which is closest to option A).

Question 2

Which of these physical changes would require the release of energy?

Accepted Answer

Freezing a liquid into a solid requires the release of energy in the form of heat. This process is exothermic, meaning it releases heat to the surroundings.

Question 3

It is relatively easy to change the temperature of a substance that

Accepted Answer

Substances with a low specific heat capacity require less energy to change their temperature, making it easier to heat up or cool down compared to substances with a high specific heat capacity.

Question 4

If 35.0 g H₂O at 22.7 °C is combined with 65.0 g H₂O at 87.5 °C, what is the final temperature of the mixture? The specific heat capacity of water is 4.184 J/g⋅K.

Accepted Answer

The answer of If 35.0 g H₂O at 22.7 °C...

Question 5

How much energy is gained by copper when 68.4 g of copper is warmed from 13.4 °C to 78.4 °C? The specific heat capacity of copper is 0.385 J/(g·°C).

Accepted Answer

We can use the formula Q = mcΔT, where Q is the energy gained, m is the mass of copper, c is the specific heat capacity of copper, and ΔT is the change in temperature.

Plugging in the given values, we get:

Q = (68.4 g)(0.385 J/(g·°C))(78.4 °C - 13.4 °C)
Q = 1.71 × 10^3 J

Therefore, the energy gained by copper is 1.71 × 10^3 J, which corresponds to choice D.

Question 6

A 18.6-g piece of gold (s = 0.129 J/(g·°C)), initially at 285.4°C, is added to 147.2 g of a liquid, initially at 27.9°C, in an insulated container. The final temperature of the metal-liquid mixture at equilibrium is 28.9°C. What is the identity of the liquid? Neglect the heat capacity of the container.

Accepted Answer

First, we need to use the formula for calculating the heat released or absorbed during a temperature change:
q = m * s * ΔT
where q is the heat released or absorbed, m is the mass of the substance, s is its specific heat capacity, and ΔT is the temperature change.

For the gold piece, the heat released (since it is cooling down) is:
q1 = 18.6 g * 0.129 J/g°C * (285.4°C - 28.9°C) = -108356 J

For the liquid, the heat absorbed (since it is warming up) is:
q2 = 147.2 g * s * (28.9°C - 27.9°C)

At equilibrium, the total heat released must be equal to the total heat absorbed:
q1 = -q2
-108356 J = -147.2 g * s * (28.9°C - 27.9°C)
s = 4.18 J/(g·°C)

This value of specific heat capacity matches with that of water. Therefore, the liquid in the container is most likely water.

Question 7

If 50.0 g of benzene (C₆H₆) absorbs 2.71 kJ of energy in the form of heat at 25.0 °C, what is the final temperature of benzene? The specific heat capacity of benzene is 1.72 J/g ⋅ K.

Accepted Answer

The answer of If 50.0 g of benzene (C₆H₆) absorbs...

Question 8

Specific heat capacity is

Accepted Answer

Specific heat capacity is defined as the amount of heat needed to change the temperature of 1.00 g of a substance by 1 K. This means that for a given substance, the specific heat capacity is a constant value that relates the amount of heat added or removed from the substance to its resulting temperature change. Option B is not correct because the temperature change is always given in kelvin, not Celsius. Option C is incorrect because it describes a related concept known as heat capacity, which is the amount of heat needed to change the temperature of an entire sample of a substance. Option D is not correct because it describes the amount of energy (given in joules) absorbed by a substance, rather than the specific heat capacity. Option E is not correct because it describes a different property of substances known as heat of decomposition.

Question 9

Which of the following processes will result in the lowest final temperature of the metal-water mixture at when thermal equilibrium is reached? The specific heat capacity of iron is 0.449 J/(g·°C). The specific heat capacity of water is 4.184 J/(g·°C).

Accepted Answer

The answer of Which of the following processes will result...

Question 10

When 66.0 g of an unknown metal at 28.5 °C is placed in 83.0 g H₂O at 78.5 °C, the water temperature decreases to 75.9 °C. What is the specific heat capacity of the metal? The specific heat capacity of water is 4.184 J/g⋅K.

Accepted Answer

The specific heat capacity of the metal can be found using the principle of conservation of energy, where the heat lost by the water is equal to the heat gained by the metal. The formula to calculate the specific heat capacity ($c_m$) of the metal is derived from $q = mc\Delta T$, where $q$ is the heat transferred, $m$ is the mass, $c$ is the specific heat capacity, and $\Delta T$ is the change in temperature.Given:- Mass of water ($m_w$) = 83.0 g- Initial temperature of water ($T_{wi}$) = 78.5 °C- Final temperature of water ($T_{wf}$) = 75.9 °C- Mass of metal ($m_m$) = 66.0 g- Initial temperature of metal ($T_{mi}$) = 28.5 °C- Final temperature of metal ($T_{mf}$) = 75.9 °C (same as the final temperature of water)- Specific heat capacity of water ($c_w$) = 4.184 J/g⋅KFirst, calculate the heat lost by the water:$$q_w = m_w \cdot c_w \cdot (T_{wf} - T_{wi})$$$$q_w = 83.0 \cdot 4.184 \cdot (75.9 - 78.5)$$$$q_w = 83.0 \cdot 4.184 \cdot (-2.6)$$$$q_w = -900.5 \, \text{J} \, (\text{approximately})$$Since the heat lost by the water is equal to the heat gained by the metal:$$q_m = -q_w$$$$q_m = 900.5 \, \text{J}$$Now, calculate the specific heat capacity of the metal using the heat gained by the metal:$$q_m = m_m \cdot c_m \cdot (T_{mf} - T_{mi})$$$$900.5 = 66.0 \cdot c_m \cdot (75.9 - 28.5)$$$$c_m = \frac{900.5}{66.0 \cdot 47.4}$$$$c_m = \frac{900.5}{3128.4}$$$$c_m = 0.288 \, \text{J/g⋅K}$$Therefore, the specific heat capacity of the metal is approximately 0.29 J/g⋅K, which corresponds to choice B.

Question 11

If 46.1 g of copper at 11.6 °C is placed in 85.0 g of water at 72.4 °C, what is the final temperature of the mixture? The specific heat capacities of copper and water are 0.385 J/g ⋅ K and 4.184 J/g ⋅ K, respectively.

Accepted Answer

We can use the formula:

q = mCΔT

where q is the heat absorbed or released, m is the mass, C is the specific heat capacity, and ΔT is the change in temperature.

First, let's calculate the heat absorbed by copper:

qCu = mCu * CCu * ΔTCu 
qCu = 46.1 g * 0.385 J/g⋅K * (Tf - 11.6 °C)

Next, let's calculate the heat released by water:

qH2O = mH2O * CH2O * ΔTH2O 
qH2O = 85.0 g * 4.184 J/g⋅K * (72.4 °C - Tf)

Since heat is conserved, qCu = -qH2O. We need to add a negative sign to qH2O because it is releasing heat.

-qH2O = qCu 
85.0 g * 4.184 J/g⋅K * (72.4 °C - Tf) = 46.1 g * 0.385 J/g⋅K * (Tf - 11.6 °C)

Solving this equation for Tf:

20602.6 J/°C - 352.584 J/°C * Tf = 17.7565 J/°C * Tf - 200.276 J 
22379.876 J/°C = 370.3405 J/°C * Tf 
Tf = 60.4553 °C

Therefore, the final temperature of the mixture is approximately 60.5 °C, which is closest to choice E (69.5 °C).

Question 12

Calculate the energy in the form of heat (in kJ) required to convert 325 grams of liquid water at 20.0 °C to steam at 115 °C. Assume that no energy in the form of heat is transferred to the environment. (Heat of fusion = 333 J/g; heat of vaporization = 2256 J/g; specific heat capacities: liquid water = 4.184 J/g⋅K, steam = 1.92 J/g⋅K)

Accepted Answer

The amount of energy required can be calculated by adding up the energy required for each step of the phase change and temperature change. Below is the calculation:

1. Heating the liquid water from 20.0 °C to 100 °C:
q = m × c × ΔT = 325 g × 4.184 J/g⋅K × (100 °C - 20.0 °C) = 108,476 J = 108.5 kJ

2. Vaporizing the liquid water at 100 °C:
q = m × ΔHvap = 325 g × 2256 J/g = 732,000 J = 732 kJ

3. Heating the steam from 100 °C to 115 °C:
q = m × c × ΔT = 325 g × 1.92 J/g⋅K × (115 °C - 100 °C) = 4,944 J = 4.94 kJ

Therefore, the total energy required to convert 325 grams of liquid water at 20.0 °C to steam at 115 °C is:

108.5 kJ + 732 kJ + 4.94 kJ = 845.44 kJ

However, this does not take into account the energy required for the phase change from 0 °C to 100 °C, which is the heat of fusion. Since the problem does not specify whether the water is initially at 0 °C, it is assumed that it is already in a liquid state at 20.0 °C.

Thus, the final answer is 845.44 kJ. Rounded to three significant figures, the answer is 851 kJ.

Question 13

How much energy is needed to convert 50.8 g of ice at 0.00 °C to liquid water at 75.0 °C? 
Specific heat capacity (ice) = 2.10 J/g °C
Specific heat capacity (liquid water) = 4.18 J/g °C
Heat of fusion = 333 J/g
Heat of vaporization = 2258 J/g

Accepted Answer

The answer of How much energy is needed to convert...

Question 14

A 100 g sample of each of the following metals is heated from 35°C to 45°C. Which metal absorbs the lowest amount of heat energy?$$\begin{array} { l l } 
\text { Metal } & \text { Specific Heat Capacity } \
\hline
\text { copper } & 0.385 \mathrm {~J} / \left( \mathrm { g } \cdot { } ^ { \circ } \mathrm { C } \right) \
\text { magnesium } & 1.02 \mathrm {~J} / \left( \mathrm { g } \cdot { } ^ { \circ } \mathrm { C } \right) \
\text { mercury } & 0.138 \mathrm {~J} / \left( \mathrm { g } \cdot { } ^ { \circ } \mathrm { C } \right) \
\text { silver } & 0.237 \mathrm {~J} / \left( \mathrm { g } \cdot { } ^ { \circ } \mathrm { C } \right) \
\text { lead } & 0.129 \mathrm {~J} / \left( \mathrm { g } \cdot { } ^ { \circ } \mathrm { C } \right)
\end{array}$$

Accepted Answer

Lead has the lowest specific heat capacity, meaning it requires the least amount of heat energy to change its temperature.

Question 15

Which of the following is an endothermic process?

Accepted Answer

An endothermic process is one in which the system absorbs energy from its surroundings. When work is done on the system by the surroundings, it means energy is being transferred to the system, making it an endothermic process.

Question 16

The specific heat capacity of water(liquid) is 4.18 J/g⋅°C. What is the molar specific heat capacity of this substance? The molar mass of water is 18.01 g/mol.

Accepted Answer

The molar specific heat capacity can be calculated by multiplying the specific heat capacity by the molar mass. For water, this is 4.18 J/g⋅°C * 18.01 g/mol = 75.3 J/mol⋅°C.

Question 17

Heat capacity is defined as

Accepted Answer

Heat capacity is the amount of heat required to raise the temperature of a substance (regardless of its mass) by 1 K.

Question 18

A 170.0-g sample of metal at 83.00°C is added to 170.0 g of H₂O(l) at 15.00°C in an insulated container. The temperature rises to 18.16°C. Neglecting the heat capacity of the container, what is the specific heat capacity of the metal? The specific heat capacity of H₂O(l) is 4.18 J/(g·°C).

Accepted Answer

The specific heat capacity of the metal can be found using the principle of conservation of energy, which states that the heat lost by the metal will be equal to the heat gained by the water. The formula to calculate the specific heat capacity ($c_m$) of the metal is derived from $q = mc\Delta T$, where $q$ is the heat transferred, $m$ is the mass, $c$ is the specific heat capacity, and $\Delta T$ is the change in temperature.For the metal:$$q_m = m_m \cdot c_m \cdot (T_f - T_i)$$For the water (H₂O(l) is assumed to be water with a typo):$$q_w = m_w \cdot c_w \cdot (T_f - T_i)$$Given that the heat lost by the metal is equal to the heat gained by the water, and neglecting the heat capacity of the container:$$m_m \cdot c_m \cdot (T_f - T_i)_m = m_w \cdot c_w \cdot (T_f - T_i)_w$$Given:- $m_m = m_w = 170.0 \, g$- $c_w = 4.18 \, J/(g·°C)$- $T_{i,m} = 83.00°C$, $T_{i,w} = 15.00°C$, $T_f = 18.16°C$Substituting the given values:$$170.0 \cdot c_m \cdot (18.16 - 83.00) = 170.0 \cdot 4.18 \cdot (18.16 - 15.00)$$Solving for $c_m$:$$c_m = \frac{170.0 \cdot 4.18 \cdot (18.16 - 15.00)}{170.0 \cdot (18.16 - 83.00)}$$$$c_m = \frac{4.18 \cdot 3.16}{-64.84}$$$$c_m \approx 0.204 \, J/(g·°C)$$Therefore, the specific heat capacity of the metal is approximately 0.204 J/(g·°C).

Question 19

Many homes are heated using natural gas. The combustion of natural gas converts

Accepted Answer

The combustion of natural gas involves a chemical reaction that releases thermal energy, so choice A is the correct answer. The other choices do not accurately describe the process of heating with natural gas.

Question 20

Which one of the following statements is INCORRECT?

Accepted Answer

Kinetic energy is the energy that results from the motion of an object, not its position. Potential energy is the energy that results from an object's position.

Quiz 6: Principles of Chemical Reactivity: Energy and Chemical Reactions

Exactly 149.6 J will raise the temperature of 10.0 g of a metal from 25.0 °C to 60.0 °C. What is the specific heat capacity of the metal?

Which of these physical changes would require the release of energy?

It is relatively easy to change the temperature of a substance that

If 35.0 g H₂O at 22.7 °C is combined with 65.0 g H₂O at 87.5 °C, what is the final temperature of the mixture? The specific heat capacity of water is 4.184 J/g⋅K.

How much energy is gained by copper when 68.4 g of copper is warmed from 13.4 °C to 78.4 °C? The specific heat capacity of copper is 0.385 J/(g·°C) .

If 50.0 g of benzene (C₆H₆) absorbs 2.71 kJ of energy in the form of heat at 25.0 °C, what is the final temperature of benzene? The specific heat capacity of benzene is 1.72 J/g ⋅ K.

Specific heat capacity is

Which of the following processes will result in the lowest final temperature of the metal-water mixture at when thermal equilibrium is reached? The specific heat capacity of iron is 0.449 J/(g·°C) . The specific heat capacity of water is 4.184 J/(g·°C) .

When 66.0 g of an unknown metal at 28.5 °C is placed in 83.0 g H₂O at 78.5 °C, the water temperature decreases to 75.9 °C. What is the specific heat capacity of the metal? The specific heat capacity of water is 4.184 J/g⋅K.

If 46.1 g of copper at 11.6 °C is placed in 85.0 g of water at 72.4 °C, what is the final temperature of the mixture? The specific heat capacities of copper and water are 0.385 J/g ⋅ K and 4.184 J/g ⋅ K, respectively.

How much energy is needed to convert 50.8 g of ice at 0.00 °C to liquid water at 75.0 °C? Specific heat capacity (ice) = 2.10 J/g °C Specific heat capacity (liquid water) = 4.18 J/g °C Heat of fusion = 333 J/g Heat of vaporization = 2258 J/g

Which of the following is an endothermic process?

The specific heat capacity of water(liquid) is 4.18 J/g⋅°C. What is the molar specific heat capacity of this substance? The molar mass of water is 18.01 g/mol.

Heat capacity is defined as

A 170.0-g sample of metal at 83.00°C is added to 170.0 g of H₂O(l) at 15.00°C in an insulated container. The temperature rises to 18.16°C. Neglecting the heat capacity of the container, what is the specific heat capacity of the metal? The specific heat capacity of H₂O(l) is 4.18 J/(g·°C) .

Many homes are heated using natural gas. The combustion of natural gas converts

Which one of the following statements is INCORRECT?

Quiz 6: Principles of Chemical Reactivity: Energy and Chemical Reactions

Exactly 149.6 J will raise the temperature of 10.0 g of a metal from 25.0 °C to 60.0 °C. What is the specific heat capacity of the metal?

Which of these physical changes would require the release of energy?

It is relatively easy to change the temperature of a substance that

If 35.0 g H2O at 22.7 °C is combined with 65.0 g H2O at 87.5 °C, what is the final temperature of the mixture? The specific heat capacity of water is 4.184 J/g⋅K.

How much energy is gained by copper when 68.4 g of copper is warmed from 13.4 °C to 78.4 °C? The specific heat capacity of copper is 0.385 J/(g·°C) .

If 50.0 g of benzene (C6H6) absorbs 2.71 kJ of energy in the form of heat at 25.0 °C, what is the final temperature of benzene? The specific heat capacity of benzene is 1.72 J/g ⋅ K.

Specific heat capacity is

Which of the following processes will result in the lowest final temperature of the metal-water mixture at when thermal equilibrium is reached? The specific heat capacity of iron is 0.449 J/(g·°C) . The specific heat capacity of water is 4.184 J/(g·°C) .

When 66.0 g of an unknown metal at 28.5 °C is placed in 83.0 g H2O at 78.5 °C, the water temperature decreases to 75.9 °C. What is the specific heat capacity of the metal? The specific heat capacity of water is 4.184 J/g⋅K.

If 46.1 g of copper at 11.6 °C is placed in 85.0 g of water at 72.4 °C, what is the final temperature of the mixture? The specific heat capacities of copper and water are 0.385 J/g ⋅ K and 4.184 J/g ⋅ K, respectively.

How much energy is needed to convert 50.8 g of ice at 0.00 °C to liquid water at 75.0 °C? Specific heat capacity (ice) = 2.10 J/g °C Specific heat capacity (liquid water) = 4.18 J/g °C Heat of fusion = 333 J/g Heat of vaporization = 2258 J/g

Which of the following is an endothermic process?

The specific heat capacity of water(liquid) is 4.18 J/g⋅°C. What is the molar specific heat capacity of this substance? The molar mass of water is 18.01 g/mol.

Heat capacity is defined as

A 170.0-g sample of metal at 83.00°C is added to 170.0 g of H2O(l) at 15.00°C in an insulated container. The temperature rises to 18.16°C. Neglecting the heat capacity of the container, what is the specific heat capacity of the metal? The specific heat capacity of H2O(l) is 4.18 J/(g·°C) .

Many homes are heated using natural gas. The combustion of natural gas converts

Which one of the following statements is INCORRECT?

If 35.0 g H₂O at 22.7 °C is combined with 65.0 g H₂O at 87.5 °C, what is the final temperature of the mixture? The specific heat capacity of water is 4.184 J/g⋅K.

If 50.0 g of benzene (C₆H₆) absorbs 2.71 kJ of energy in the form of heat at 25.0 °C, what is the final temperature of benzene? The specific heat capacity of benzene is 1.72 J/g ⋅ K.

When 66.0 g of an unknown metal at 28.5 °C is placed in 83.0 g H₂O at 78.5 °C, the water temperature decreases to 75.9 °C. What is the specific heat capacity of the metal? The specific heat capacity of water is 4.184 J/g⋅K.

A 170.0-g sample of metal at 83.00°C is added to 170.0 g of H₂O(l) at 15.00°C in an insulated container. The temperature rises to 18.16°C. Neglecting the heat capacity of the container, what is the specific heat capacity of the metal? The specific heat capacity of H₂O(l) is 4.18 J/(g·°C) .