Question 1

In an endothermic process, heat is absorbed by the system.

Accepted Answer

In an endothermic process, the system absorbs heat from its surroundings, resulting in an increase in its internal energy. Therefore, the statement is true.

Question 2

The combustion of one mole of benzene, C₆H₆, in oxygen liberates 3268 kJ of heat.The products of the reaction are carbon dioxide and water. How much heat is given off when 183 g of oxygen are reacted with excess benzene?

Accepted Answer

The answer of The combustion of one mole of benzene,...

Question 3

If 2Mg(s)+ O₂(g)$\rarr$2MgO(s), $\Delta$H° = -1203.6 kJ/mol. For Mg(s)+ (1/2)O₂(g)$\rarr$MgO(s), the enthalpy change is $\Delta$H = -601.8 kJ/mol.

Accepted Answer

The given chemical equation and values of enthalpy change follow the law of Hess's law, which states that the enthalpy change in a chemical reaction is independent of the pathway between the initial and final states of the system. Therefore, the enthalpy change for the second equation can be obtained by subtracting the enthalpy change of the first equation from the given value. Subtracting -1203.6 kJ/mol from -601.8 kJ/mol gives -601.8 kJ/mol as the enthalpy change for the second equation, which matches the given value. Hence, the statement is true.

Question 4

The heat absorbed by a system at constant pressure is equal to $\Delta$E + P$\Delta$V.

Accepted Answer

This is the enthalpy equation, which states that the heat absorbed by a system at constant pressure (enthalpy change, ΔH) is equal to the sum of the internal energy change (ΔU) and the product of pressure and volume change (PΔV): ΔH = ΔU + PΔV.

Question 5

The heat of hydration ($\Delta$H_hydr)of ions is always endothermic.

Accepted Answer

The heat of hydration of ions is typically exothermic because energy is released when water molecules surround and interact with ions.

Question 6

The specific heats of water and iron are 4.184 and 0.444 J/g°C, respectively. When equal masses of water and iron both absorb the same amount of heat, the temperature increase of the water will be 5.42 times greater than that of the iron.

Accepted Answer

Let the masses of water and iron be m.
Therefore, the heat absorbed by water and iron will be equal and given by:
Q = m x s x ΔT, where s is the specific heat and ΔT is the temperature change.
For water, we have: Q = m x 4.184 x ΔT
For iron, we have: Q = m x 0.444 x ΔT
Since Q is equal for both, we can equate the expressions:
m x 4.184 x ΔT = m x 0.444 x ΔT
Canceling out the masses and simplifying, we get:
ΔT_water = 5.42 x ΔT_iron
This shows that the temperature increase of water is 5.42 times greater than that of iron, which means the given statement is true.

Question 7

The heat capacity of 20.0 g of water is 83.7 J/°C.

Accepted Answer

This is a true statement. The heat capacity of water is approximately 4.18 J/g°C, so the heat capacity of 20.0 g of water would be 20.0 g x 4.18 J/g°C = 83.7 J/°C.

Question 8

A home aquarium is an example of an open system.

Accepted Answer

A home aquarium is an example of an open system because energy and matter can flow in and out of the system. The fish and plants inside the aquarium consume oxygen and release carbon dioxide, while food and water are added from outside the system. Similarly, waste produced by the fish and plants is removed from the system.

Question 9

Chemical reactions in a bomb calorimeter occur at constant pressure.

Accepted Answer

The answer of Chemical reactions in a bomb calorimeter occur...

Question 10

The work done on the surroundings by the expansion of a gas is w = -P$\Delta$V.

Accepted Answer

This is the correct formula for work done by a gas during expansion, where P is the pressure, ΔV is the change in volume, and F1S1 is the force on the gas due to the surroundings at constant pressure. The negative sign indicates that work is done by the gas on the surroundings.

Question 11

A feverish student weighing 75 kilograms was immersed in 400.kg of water at 4.0°C to try to reduce the fever.The student's body temperature dropped from 40.0°C to 37.0°C.Assuming the specific heat of the student to be 3.77 J/g·°C, what was the final temperature of the water?

Accepted Answer

The answer of A feverish student weighing 75 kilograms was...

Quiz 6: Thermo-Chemistry

In an endothermic process, heat is absorbed by the system.

The combustion of one mole of benzene, C₆H₆, in oxygen liberates 3268 kJ of heat.The products of the reaction are carbon dioxide and water. How much heat is given off when 183 g of oxygen are reacted with excess benzene?

If 2Mg(s)+ O₂(g) $\rarr$ 2MgO(s), $\Delta$ H° = -1203.6 kJ/mol. For Mg(s)+ (1/2)O₂(g) $\rarr$ MgO(s), the enthalpy change is $\Delta$ H = -601.8 kJ/mol.

The heat absorbed by a system at constant pressure is equal to $\Delta$ E + P $\Delta$ V.

The heat of hydration ( $\Delta$ H_hydr)of ions is always endothermic.

The specific heats of water and iron are 4.184 and 0.444 J/g°C, respectively. When equal masses of water and iron both absorb the same amount of heat, the temperature increase of the water will be 5.42 times greater than that of the iron.

The heat capacity of 20.0 g of water is 83.7 J/°C.

A home aquarium is an example of an open system.

Chemical reactions in a bomb calorimeter occur at constant pressure.

The work done on the surroundings by the expansion of a gas is w = -P $\Delta$ V.

A feverish student weighing 75 kilograms was immersed in 400.kg of water at 4.0°C to try to reduce the fever.The student's body temperature dropped from 40.0°C to 37.0°C.Assuming the specific heat of the student to be 3.77 J/g·°C, what was the final temperature of the water?

Quiz 6: Thermo-Chemistry

In an endothermic process, heat is absorbed by the system.

The combustion of one mole of benzene, C6H6, in oxygen liberates 3268 kJ of heat.The products of the reaction are carbon dioxide and water. How much heat is given off when 183 g of oxygen are reacted with excess benzene?

If 2Mg(s)+ O2(g) →\rarr→ 2MgO(s), Δ\DeltaΔ H° = -1203.6 kJ/mol. For Mg(s)+ (1/2)O2(g) →\rarr→ MgO(s), the enthalpy change is Δ\DeltaΔ H = -601.8 kJ/mol.

The heat absorbed by a system at constant pressure is equal to Δ\DeltaΔ E + P Δ\DeltaΔ V.

The heat of hydration ( Δ\DeltaΔ Hhydr)of ions is always endothermic.

The specific heats of water and iron are 4.184 and 0.444 J/g°C, respectively. When equal masses of water and iron both absorb the same amount of heat, the temperature increase of the water will be 5.42 times greater than that of the iron.

The heat capacity of 20.0 g of water is 83.7 J/°C.

A home aquarium is an example of an open system.

Chemical reactions in a bomb calorimeter occur at constant pressure.

The work done on the surroundings by the expansion of a gas is w = -P Δ\DeltaΔ V.

A feverish student weighing 75 kilograms was immersed in 400.kg of water at 4.0°C to try to reduce the fever.The student's body temperature dropped from 40.0°C to 37.0°C.Assuming the specific heat of the student to be 3.77 J/g·°C, what was the final temperature of the water?

The combustion of one mole of benzene, C₆H₆, in oxygen liberates 3268 kJ of heat.The products of the reaction are carbon dioxide and water. How much heat is given off when 183 g of oxygen are reacted with excess benzene?

If 2Mg(s)+ O₂(g) $\rarr$ 2MgO(s), $\Delta$ H° = -1203.6 kJ/mol. For Mg(s)+ (1/2)O₂(g) $\rarr$ MgO(s), the enthalpy change is $\Delta$ H = -601.8 kJ/mol.

The heat absorbed by a system at constant pressure is equal to $\Delta$ E + P $\Delta$ V.

The heat of hydration ( $\Delta$ H_hydr)of ions is always endothermic.

The work done on the surroundings by the expansion of a gas is w = -P $\Delta$ V.