Thermodynamics Test

Result

Thermodynamics Test - 23

Score
-
out of -
Rank
-
out of -

TIME Taken - -

SHARING IS CARING

If our Website helped you a little, then kindly spread our voice using Social Networks. Spread our word to your readers, friends, teachers, students & all those close ones who deserve to know what you know now.

Weekly Quiz Competition

Question 1
1 / -0

Mark the point where the temperature of $$H_2O$$ is changing at $$4.18 J/g^o$$C(or $$1$$ $$cal/g^oC$$)?

A
A

B
B

C
C

D
D

E
E

Solution

At point (C) the temperature of the water is changing at $$ 4.18J/g ^ oC$$

The specific heat of liquid water is $$4.18J/g ^ oC$$.

Thus the section (C) of the curve corresponds to the region where the temperature of the water is heated from $$0^0 C$$ to $$100^0 C$$.

Hence, the correct option is C.
Question 2
1 / -0

According to Hess's law, the heat of reaction depends upon

A
initial condition of reactants

B
initial and final conditions of reactants

C
intermediate path of the reaction

D
end conditions of reactants

Solution

According to Hess's law, the heat of reaction depends upon Initial and final conditions of reactants. The the heat of reaction is independant of the intermediate path of the reaction. For example, the heat of the reaction for the reaction $$\displaystyle A \rightarrow D$$ is equal to the sum of the heats of the reactions $$\displaystyle A \rightarrow B \\ B \rightarrow C \\ C \rightarrow D$$
Question 3
1 / -0

If $$C+{O}_{2}.\longrightarrow {CO}_{2}+94.2kcal$$
$${H}_{2}+\cfrac{1}{2}{O}_{2}\longrightarrow {H}_{2}+68.3kcal$$
$${CH}_{4}+2{O}_{2}\longrightarrow {CO}_{2}+2{H}_{2}O+210.8kcal$$
Then, the heat of formation of methane will be

A
$$47.3kcal$$

B
$$20.0kcal$$

C
$$45.9kcal$$

D
$$-47.3kcal$$

Solution

$$C+{O}_{2}\longrightarrow {CO}_{2}+94.3kcal.........(i)$$
$${H}_{2}+\cfrac{1}{2}{O}_{2}\longrightarrow {H}_{2}O+68.3kcal.......(ii)$$
On multiplying Eq.$$(ii)$$ by $$2$$ and then adding in Eq.$$(i)$$, we get
$$C+2{H}_{2}+2{O}_{2}\longrightarrow {CO}_{2}+2{H}_{2}O+230.8kcal.....(iii)$$
On substracting, adding the following equation from Eq. $$(iii)$$
$${CH}_{4}+2{O}_{2}\longrightarrow {CO}_{2}+2{H}_{2}O+210.8kcal$$
we get
$$C+2{H}_{2}\longrightarrow {CH}_{4}+20kcal$$
Question 4
1 / -0

10 g of liquid at 300K is heated to 350 K. The liquid absorbs 6 kcals. What is the specific heat of the liquid (in $$cal/ \displaystyle { g }^{ \circ }C$$)?

A
6

B
12

C
60

D
120

Solution

$$Q=nC\triangle T$$ where $$C$$=specific heat of the liquid
$$6KCal=Q$$

$$6\times 10^3 Cal=Q$$

So, $$6 \times 10^3=10\times C\times (350-300)K$$

$$\Rightarrow \cfrac {6\times 10^3}{10\times 50}=C$$

$$\Rightarrow C=12$$.
Question 5
1 / -0

Statement I
As ice absorbs heat and begins to melt, its temperature remains constant
Because
Statement II
Changes of state bring about changes in a substances potential energy, not in its kinetic energy

A
Statement 1 and Statement 2 are correct and Statement 2 is the correct explanation of Statement 1

B
Both the Statement 1 and Statement 2 are correct and Statement 2 is not the correct explanation of Statement 1.

C
Statement 1 is correct but Statement 2 is not correct.

D
Statement 1 is not correct but Statement 2 is correct.

E
Both the Statement 1 and Statement 2 are not correct.

Solution

As ice absorbs heat and begins to melt, its temperature remains constant, this statement is true because phase change from solid to liquid occurs at constant temperature. This is because change of state brings about changes in a substance's potential energy, not in its kinetic energy,so both statements are correct and second statement is correct explanation of first.
Question 6
1 / -0

If 100.0 J of energy is added to 50.0 g of Cu, initially at $$25.0^o C$$, what will be the final temperature? (Specific heat capacity = 0.382 J/ C.g )

A
$$31.2^o C$$

B
$$30.24^o C$$

C
$$25.2^o C$$

D
$$25.19^o C$$

E
$$19.8^o C$$

Solution

let T deg C be the final temperature.
$$\displaystyle q = mS \Delta T$$
$$\displaystyle q = 100.0 $$ J = energy added
$$\displaystyle m = 50.0$$ g = mass of Cu
$$\displaystyle S = 0.382$$ J/C.g = the specific heat of Cu
$$\displaystyle \Delta T = T - 25.0$$ = temperature difference.
Substite values in the above equation.
$$\displaystyle 100.0 = 50.0 \times 0.382 \times (T-25.0) $$
$$\displaystyle 5.235= T-25.0$$
$$\displaystyle T = 30.24 ^oC $$
Question 7
1 / -0

Two substances P and Q when brought together, form substance R with the evolution of heat. The properties of R are different from both P and Q. What is substance R?

A
A compound

B
An element

C
A metal

D
A mixture

Solution

Since the substance $$R$$ is a mixture of two substances, it may either be a mixture or a compound
In a mixture the constituents retain their properties while in a compound, they lose their properties.
Since the question mentions that $$R$$ has different property from both $$P$$ and $$Q$$, hence it must be a compound
Question 8
1 / -0

Which statement is correct about heat?

A
It is a measure of the transfer of energy due a temperature difference

B
The heat transfer is always from hot to cold

C
The heat absorbed by the surroundings equals the heat released by the system

D
The amount of heat lost or gained during a reaction is directly related to the enthalpy change of the reaction.

E
All answers are correct

Solution

All answers about heat are correct
A
It is a measure of the transfer of energy due a temperature difference. When two bodies have different temperatures, heat will be exchanged till thermal equilibrium is attained.
B
The heat transfer is always from hot to cold. Thus the body at higher temperature will lose heat and the body at lower temperature will gain heat.
C
The heat absorbed by the surroundings equals the heat released by the system
For example, if system releases 500 J heat, the surrounding will absorb 500 J heat.
D
The amount of heat lost or gained during a reaction is directly related to the enthalpy change of the reaction. The enthalpy change is the difference between the heat content of products and the heat content of reactants.
Question 9
1 / -0

Hess's Law is used

A
When a directly measured enthalpy change of reaction is not available

B
To calculate an enthalpy change value through multiple steps

C
Because enthalpy is a State Function

D
As an easy way to calculate the enthalpy change of a reaction

E
All of these options(A,B,C,D) are correct

Solution

All of these options are correct.
Hess's Law is used

A) When a directly measured enthalpy change of reaction is not available
B) To calculate an enthalpy change value through multiple steps
C) Because enthalpy is a State Function
E) As an easy way to calculate the enthalpy change of a reaction

According to Hess Law, the change in enthalpy for a reaction is the same whether the reaction takes place in one or more steps. The Hess's law can also be stated as the enthalpy change for a chemical reaction is the same regardless of the path followed by the reaction.
Question 10
1 / -0

A spontaneous reaction occurs:

A
by itself and quickly

B
with outside intervention and quickly

C
by itself and slowly

D
with outside intervention and slowly

E
by itself but it has now effect on how fast the reaction takes

Solution

A spontaneous reaction occurs by itself but it has no effect on how fast the reaction takes. A spontaneous reaction may be very fast but another spontaneous reaction may be very slow.

User

Question Analysis

Correct -
Wrong -
Skipped -

My Perfomance

Score
-
out of -
Rank
-
out of -

Re-Attempt Weekly Quiz Competition

Thermodynamics Test - 23

Result

Thermodynamics Test - 23

Score

-

Rank

-

SHARING IS CARING

Question 1

A

B

C

D

E

Solution

Question 2

initial condition of reactants

initial and final conditions of reactants

intermediate path of the reaction

end conditions of reactants

Solution

Question 3

$$47.3kcal$$

$$20.0kcal$$

$$45.9kcal$$

$$-47.3kcal$$

Solution

Question 4

6

12

60

120

Solution

Question 5

Statement 1 and Statement 2 are correct and Statement 2 is the correct explanation of Statement 1

Both the Statement 1 and Statement 2 are correct and Statement 2 is not the correct explanation of Statement 1.

Statement 1 is correct but Statement 2 is not correct.

Statement 1 is not correct but Statement 2 is correct.

Both the Statement 1 and Statement 2 are not correct.

Solution

Question 6

$$31.2^o C$$

$$30.24^o C$$

$$25.2^o C$$

$$25.19^o C$$

$$19.8^o C$$

Solution

Question 7

A compound

An element

A metal

A mixture

Solution

Question 8

It is a measure of the transfer of energy due a temperature difference

The heat transfer is always from hot to cold

The heat absorbed by the surroundings equals the heat released by the system

The amount of heat lost or gained during a reaction is directly related to the enthalpy change of the reaction.

All answers are correct

Solution

Question 9

When a directly measured enthalpy change of reaction is not available

To calculate an enthalpy change value through multiple steps

Because enthalpy is a State Function

As an easy way to calculate the enthalpy change of a reaction

All of these options(A,B,C,D) are correct

Solution

Question 10

by itself and quickly

with outside intervention and quickly

by itself and slowly

with outside intervention and slowly

by itself but it has now effect on how fast the reaction takes

Solution

User

Question Analysis

My Perfomance

Score

-

Rank