Question 1

The combustion of benzoic acid,C₇H₆O₂,can be used to determine the heat capacity of a bomb calorimeter.The heat evolved per mole of benzoic acid combusted is 3.09 × 10³ kJ.If the combustion of 1.000 g of benzoic acid increases the temperature of a calorimeter by 7.53°C.What is the heat capacity of the calorimeter?

Accepted Answer

B

Question 2

All of the following statements are true EXCEPT

Accepted Answer

The value of q is positive in an endothermic process, as heat flows from the surroundings into the system. A negative value of q indicates an exothermic process, where heat flows from the system into the surroundings.

Question 3

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

Accepted Answer

C

Question 4

If 495 J is required to change the temperature of 12.7 g of sodium chloride from 75.0°C to 135°C,what is the specific heat of sodium chloride?

Accepted Answer

The answer of If 495 J is required to change...

Question 5

When 1.75 g of CaCl₂ dissolves in 125 g of water in a coffee-cup calorimeter,the temperature increases by 2.44°C.What is the heat change per mole of CaCl₂ dissolved in water? Assume that all the heat is absorbed by the water (c = 4.18 J/g⋅°C).

Accepted Answer

The answer of When 1.75 g of CaCl₂ dissolves in...

Question 6

How many joules are equivalent to 1.50 × 10³ calories?

Accepted Answer

1 calorie is equivalent to 4.184 joules. Therefore, 1.50 × 10^3 calories is equivalent to 1.50 × 10^3 × 4.184 = 6.28 × 10^3 joules.

Question 7

Water has a specific heat of 4.18 J/g⋅°C.If 35.0 g of water at 98.8°C loses 4.94 kJ of heat,what is the final temperature of the water?

Accepted Answer

The answer of Water has a specific heat of 4.18...

Question 8

Isooctane is a primary component of gasoline and gives gasoline its octane rating.Burning 1.00 mL of isooctane (d = 0.688g/mL)releases 33.0 kJ of heat.When 10.0 mL of isooctane is burned in a bomb calorimeter,the temperature in the bomb increases from 23.2°C to 66.5°C.What is the heat capacity of the bomb calorimeter?

Accepted Answer

The heat released by burning 10.0 mL of isooctane is 330 kJ (since 1.00 mL releases 33.0 kJ). The temperature change is 66.5°C - 23.2°C = 43.3°C. The heat capacity of the calorimeter is calculated as heat released divided by temperature change: 330 kJ / 43.3°C = 7.62 kJ/°C.

Question 9

Acetylene,C₂H₂,is a gas used in welding.The molar enthalpy of combustion for acetylene is -2599 kJ.A mass of 0.338 g C₂H₂(g)is combusted in a bomb calorimeter.If the heat capacity of the calorimeter is 5.54 kJ/°C,what is the temperature increase of the bomb calorimeter?

Accepted Answer

First, calculate the moles of acetylene (C2H2) combusted: 0.338 g / 26.04 g/mol (molar mass of C2H2) = 0.01298 mol. Then, calculate the heat released: 0.01298 mol * -2599 kJ/mol = -33.74 kJ. Finally, calculate the temperature increase: -33.74 kJ / 5.54 kJ/°C = -6.09°C. Since temperature increase is a magnitude, the answer is 6.09°C.

Question 10

A coffee-cup calorimeter contains 10.0 g of water at 59.00°C.If 3.00 g gold at 15.20°C is placed in the calorimeter,what is the final temperature of the water in the calorimeter? The specific heat of water is 4.18 J/g⋅°C;the specific heat of gold is 0.128 J/g⋅°C.

Accepted Answer

First, we need to calculate the amount of heat released by the gold and gained by the water:
$q_{Au} = m_{Au}c_{Au}\Delta T_{Au} = 3.00g 	imes 0.128 (J/g\cdot°C) 	imes (59.00°C-T_{final})$
$q_{H_2O} = m_{H_2O}c_{H_2O}\Delta T_{H_2O} = 10.0g 	imes 4.18 (J/g\cdot°C) 	imes (T_{final}-59.00°C)$

Since $q_{Au}=-q_{H_2O}$ (heat lost by one substance is equal to the heat gained by another), we can set them equal to each other and solve for Tfinal:

$3.00g 	imes 0.128 (J/g\cdot°C) 	imes (59.00°C-T_{final}) = 10.0g 	imes 4.18 (J/g\cdot°C) 	imes (T_{final}-59.00°C)$

Solving for Tfinal gives: 
$T_{final} = 58.60°C$

Therefore, the answer is B.

Question 11

Specific heat (c)is defined as

Accepted Answer

Specific heat is defined as the amount of heat required to raise one gram of a substance by one degree Celsius. Therefore, option A is the most accurate definition of specific heat.

Question 12

When 10.0 g KOH is dissolved in 100.0 g of water in a coffee-cup calorimeter,the temperature rises from 25.18 °C to 47.53 °C.What is the enthalpy change per gram of KOH dissolved in the water? Assume that the solution has a specific heat capacity of 4.18 J/g⋅K.

Accepted Answer

The answer of When 10.0 g KOH is dissolved in...

Question 13

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⋅°C.

Accepted Answer

To find the specific heat capacity of the metal, we use the principle of conservation of energy, where the heat lost by the water is equal to the heat gained by the metal. The formula for heat (q) is q = mcΔT, where m is mass, c is specific heat capacity, and ΔT is the change in temperature.For water:- Mass (m) = 83.0 g- Specific heat capacity (c) = 4.184 J/g°C- Change in temperature (ΔT) = 75.9°C - 78.5°C = -2.6°CFor the metal:- Mass (m) = 66.0 g- Specific heat capacity (c) = unknown- Change in temperature (ΔT) = 75.9°C - 28.5°C = 47.4°CSetting the heat gained by the metal equal to the heat lost by the water:$$q_{metal} = q_{water}$$$$m_{metal}c_{metal}\Delta T_{metal} = m_{water}c_{water}\Delta T_{water}$$$$66.0 \times c_{metal} \times 47.4 = 83.0 \times 4.184 \times (-2.6)$$Solving for $c_{metal}$:$$c_{metal} = \frac{83.0 \times 4.184 \times (-2.6)}{66.0 \times 47.4}$$$$c_{metal} \approx 0.29 \, \text{J/g°C}$$Therefore, the specific heat capacity of the metal is approximately 0.29 J/g°C.

Question 14

TThe heat capacity of iron is 0.446 J/°C.How much heat is required to change the temperature of 5.00 grams of iron by 50.0°C?

Accepted Answer

To calculate the heat required, we use the formula:

q = m * c * ∆T

where:
q = heat required (in Joules)
m = mass of the substance (in grams)
c = specific heat capacity of the substance (in J/g ºC)
∆T = change in temperature (in ºC)

Substituting the given values in the formula, we get:

q = 5.00 g * 0.446 J/g ºC * 50.0 ºC
q = 112 J

Therefore, the heat required to change the temperature of 5.00 grams of iron by 50.0°C is 112 J.

Question 15

A coffee-cup calorimeter contains 50.0 g of water at 60.51°C.A 12.4 g piece of graphite at 24.21°C is placed in the calorimeter.The final temperature of the water and the carbon is 59.02°C.Calculate the specific heat of carbon.The specific heat of water is 4.18 J/g⋅°C.

Accepted Answer

First, we need to find the heat lost by the water:
q(water) = m(water) × c(water) × ΔT
q(water) = 50.0 g × 4.18 J/g°C × (60.51°C - 59.02°C) = 314.7 J

Next, we need to find the heat gained by the carbon:
q(carbon) = m(carbon) × c(carbon) × ΔT
q(carbon) = 12.4 g × c(carbon) × (59.02°C - 24.21°C)

Since the calorimeter is well-insulated, we can assume that the heat lost by the water is equal to the heat gained by the carbon:
q(water) = -q(carbon)

Substituting the values and solving for c(carbon):
314.7 J = -12.4 g × c(carbon) × (59.02°C - 24.21°C)
c(carbon) = 0.721 J/g°C

Therefore, the specific heat of carbon is 0.721 J/g°C. The answer is D.

Question 16

Commercial cold packs consist of solid ammonium nitrate and water.NH₄NO₃ absorbs 25.69 kJ of heat per mole dissolved in water.In a coffee-cup calorimeter,5.60 g NH₄NO₃ is dissolved in 100.0 g of water at 22.0°C.What is the final temperature of the solution? Assume that the solution has a specific heat capacity of 4.18 J/g⋅°C.

Accepted Answer

First, convert the mass of ammonium nitrate (NH4NO3) to moles: $5.60 \, \text{g} \times \frac{1 \, \text{mol}}{80.04 \, \text{g/mol}} = 0.07 \, \text{mol}$. The heat absorbed when this amount dissolves is $0.07 \, \text{mol} \times 25.69 \, \text{kJ/mol} = 1.7983 \, \text{kJ} = 1798.3 \, \text{J}$. Since the heat is absorbed by the solution, it's lost by the water, so we use $q = mc\Delta T$ to find the temperature change, where $m = 100.0 \, \text{g} + 5.60 \, \text{g}$ (since the mass of the solution is the mass of the water plus the mass of the ammonium nitrate), $c = 4.18 \, \text{J/g°C}$, and $q = -1798.3 \, \text{J}$ (negative because the water loses heat). Solving for $\Delta T$, we find $\Delta T = \frac{q}{mc} = \frac{-1798.3 \, \text{J}}{(105.6 \, \text{g})(4.18 \, \text{J/g°C})} = -4.1°C$. The final temperature is $22.0°C - 4.1°C = 17.9°C$.

Question 17

A chemical reaction in a bomb calorimeter evolves 3.15 kJ of heat.If the temperature of the calorimeter is raised from 19.19°C to 22.03°C,what is the heat capacity of the calorimeter?

Accepted Answer

The heat capacity of the calorimeter can be calculated using the formula: heat capacity = heat evolved / temperature change. The temperature change is 22.03°C - 19.19°C = 2.84°C. Therefore, the heat capacity = 3.15 kJ / 2.84°C = 1.11 kJ/°C.

Question 18

Aluminum has a specific heat of 0.902 J/g⋅°C.How many joules of heat are required to change the temperature of 8.50 grams of aluminum from 25.0°C to 93.4°C?

Accepted Answer

Explanation:The amount of heat required to change the temperature of a substance is given by the equation:Q = m * c * ΔTwhere:Q is the heat energy in joulesm is the mass of the substance in gramsc is the specific heat of the substance in J/g⋅°CΔT is the change in temperature in °CIn this problem, we have:m = 8.50 gc = 0.902 J/g⋅°CΔT = 93.4°C - 25.0°C = 68.4°CPlugging these values into the equation, we get:Q = 8.50 g * 0.902 J/g⋅°C * 68.4°C = 524 JTherefore, the correct answer is E) 524 J.

Question 19

Copper has a specific heat of 0.382 J/g⋅°C.The temperature of an unknown mass of copper increases by 4.50°C when it absorbs 3.97 J of heat.What is the mass of the copper?

Accepted Answer

The mass of the copper can be calculated using the formula $q = mc\Delta T$, where $q$ is the heat absorbed, $m$ is the mass, $c$ is the specific heat capacity, and $\Delta T$ is the change in temperature. Rearranging for $m$, we get $m = \frac{q}{c\Delta T}$. Plugging in the given values, $m = \frac{3.97 \, \text{J}}{0.382 \, \text{J/g}^\circ\text{C} \times 4.50^\circ\text{C}} = 2.31 \, \text{g}$.

Question 20

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⋅°C.

Accepted Answer

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

Quiz 8: Thermochemistry

All of the following statements are true EXCEPT

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

If 495 J is required to change the temperature of 12.7 g of sodium chloride from 75.0°C to 135°C,what is the specific heat of sodium chloride?

When 1.75 g of CaCl₂ dissolves in 125 g of water in a coffee-cup calorimeter,the temperature increases by 2.44°C.What is the heat change per mole of CaCl₂ dissolved in water? Assume that all the heat is absorbed by the water (c = 4.18 J/g⋅°C) .

How many joules are equivalent to 1.50 × 10³ calories?

Water has a specific heat of 4.18 J/g⋅°C.If 35.0 g of water at 98.8°C loses 4.94 kJ of heat,what is the final temperature of the water?

Acetylene,C₂H₂,is a gas used in welding.The molar enthalpy of combustion for acetylene is -2599 kJ.A mass of 0.338 g C₂H₂(g) is combusted in a bomb calorimeter.If the heat capacity of the calorimeter is 5.54 kJ/°C,what is the temperature increase of the bomb calorimeter?

A coffee-cup calorimeter contains 10.0 g of water at 59.00°C.If 3.00 g gold at 15.20°C is placed in the calorimeter,what is the final temperature of the water in the calorimeter? The specific heat of water is 4.18 J/g⋅°C;the specific heat of gold is 0.128 J/g⋅°C.

Specific heat (c) is defined as

When 10.0 g KOH is dissolved in 100.0 g of water in a coffee-cup calorimeter,the temperature rises from 25.18 °C to 47.53 °C.What is the enthalpy change per gram of KOH dissolved in the water? Assume that the solution has a specific heat capacity of 4.18 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⋅°C.

TThe heat capacity of iron is 0.446 J/°C.How much heat is required to change the temperature of 5.00 grams of iron by 50.0°C?

A coffee-cup calorimeter contains 50.0 g of water at 60.51°C.A 12.4 g piece of graphite at 24.21°C is placed in the calorimeter.The final temperature of the water and the carbon is 59.02°C.Calculate the specific heat of carbon.The specific heat of water is 4.18 J/g⋅°C.

A chemical reaction in a bomb calorimeter evolves 3.15 kJ of heat.If the temperature of the calorimeter is raised from 19.19°C to 22.03°C,what is the heat capacity of the calorimeter?

Aluminum has a specific heat of 0.902 J/g⋅°C.How many joules of heat are required to change the temperature of 8.50 grams of aluminum from 25.0°C to 93.4°C?

Copper has a specific heat of 0.382 J/g⋅°C.The temperature of an unknown mass of copper increases by 4.50°C when it absorbs 3.97 J of heat.What is the mass of the copper?

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⋅°C.

Quiz 8: Thermochemistry

All of the following statements are true EXCEPT

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

If 495 J is required to change the temperature of 12.7 g of sodium chloride from 75.0°C to 135°C,what is the specific heat of sodium chloride?

When 1.75 g of CaCl2 dissolves in 125 g of water in a coffee-cup calorimeter,the temperature increases by 2.44°C.What is the heat change per mole of CaCl2 dissolved in water? Assume that all the heat is absorbed by the water (c = 4.18 J/g⋅°C) .

How many joules are equivalent to 1.50 × 103 calories?

Water has a specific heat of 4.18 J/g⋅°C.If 35.0 g of water at 98.8°C loses 4.94 kJ of heat,what is the final temperature of the water?

Acetylene,C2H2,is a gas used in welding.The molar enthalpy of combustion for acetylene is -2599 kJ.A mass of 0.338 g C2H2(g) is combusted in a bomb calorimeter.If the heat capacity of the calorimeter is 5.54 kJ/°C,what is the temperature increase of the bomb calorimeter?

A coffee-cup calorimeter contains 10.0 g of water at 59.00°C.If 3.00 g gold at 15.20°C is placed in the calorimeter,what is the final temperature of the water in the calorimeter? The specific heat of water is 4.18 J/g⋅°C;the specific heat of gold is 0.128 J/g⋅°C.

Specific heat (c) is defined as

When 10.0 g KOH is dissolved in 100.0 g of water in a coffee-cup calorimeter,the temperature rises from 25.18 °C to 47.53 °C.What is the enthalpy change per gram of KOH dissolved in the water? Assume that the solution has a specific heat capacity of 4.18 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⋅°C.

TThe heat capacity of iron is 0.446 J/°C.How much heat is required to change the temperature of 5.00 grams of iron by 50.0°C?

A coffee-cup calorimeter contains 50.0 g of water at 60.51°C.A 12.4 g piece of graphite at 24.21°C is placed in the calorimeter.The final temperature of the water and the carbon is 59.02°C.Calculate the specific heat of carbon.The specific heat of water is 4.18 J/g⋅°C.

A chemical reaction in a bomb calorimeter evolves 3.15 kJ of heat.If the temperature of the calorimeter is raised from 19.19°C to 22.03°C,what is the heat capacity of the calorimeter?

Aluminum has a specific heat of 0.902 J/g⋅°C.How many joules of heat are required to change the temperature of 8.50 grams of aluminum from 25.0°C to 93.4°C?

Copper has a specific heat of 0.382 J/g⋅°C.The temperature of an unknown mass of copper increases by 4.50°C when it absorbs 3.97 J of heat.What is the mass of the copper?

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⋅°C.

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

When 1.75 g of CaCl₂ dissolves in 125 g of water in a coffee-cup calorimeter,the temperature increases by 2.44°C.What is the heat change per mole of CaCl₂ dissolved in water? Assume that all the heat is absorbed by the water (c = 4.18 J/g⋅°C) .

How many joules are equivalent to 1.50 × 10³ calories?

Acetylene,C₂H₂,is a gas used in welding.The molar enthalpy of combustion for acetylene is -2599 kJ.A mass of 0.338 g C₂H₂(g) is combusted in a bomb calorimeter.If the heat capacity of the calorimeter is 5.54 kJ/°C,what is the temperature increase of the bomb calorimeter?

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⋅°C.

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⋅°C.