Thermodynamics Test

Question 1
1 / -0

Using the data provided, calculate the multiple bond energy (kJ / mol) of a $$C=C$$ bond in $$C_{2}H_{2}$$. (Take the bond energy of a C-H bond as 350 kJ / mol)

$$2C(s) + H_{2}(g) \rightarrow C_{2}H_{2}(g)$$ $$\Delta H = 225 kJ / mol$$
$$2C(s)\rightarrow 2C(g);\Delta H= 1410kJ mol^{-1}$$
$$H_2(g)\rightarrow 2H(g);\Delta H= 330kJ mol^{-1}$$

A
1165

B
837

C
865

D
815

Question 2
1 / -0

For the reaction between $$CO_2$$ and graphite
$$CO_2 (g) + C(s) \rightarrow 2CO(g)$$
$$\Delta H = 170.0 KJ and \Delta s = 170 JK^{-1}$$. The reaction is spontaneous at

A
298 K

B
500 K

C
900 K

D
none of the above

Question 3
1 / -0

An endothermic reaction is spontaneous if

A
$$\Delta H> T\Delta S$$

B
$$\Delta H< T\Delta S$$

C
$$\Delta H= T\Delta S$$

D
$$T\Delta S=0$$

Question 4
1 / -0

For the reaction,$$A\rightarrow B,\Delta H=+ve,\Delta S=-ve$$ This reaction is

A
non-spontaneous at all temperature

B
non-spontaneous at low temperature

C
non-spontaneous at high temperature

D
spontaneous at high temperature

Question 5
1 / -0

$$\begin{array}{l}N{H_3}\left( g \right) + 3C{l_2} \mathbin{\lower.3ex\hbox{$\buildrel\textstyle\rightarrow\over{\smash{\leftarrow}\vphantom{_{\vbox to.5ex{\vss}}}}$}} NC{l_4}\left( g \right) + 3HCl: - \Delta {H_1}\\{N_2}\left( g \right) + 3{H_2}\left( g \right) \mathbin{\lower.3ex\hbox{$\buildrel\textstyle\rightarrow\over{\smash{\leftarrow}\vphantom{_{\vbox to.5ex{\vss}}}}$}} 2N{H_3}\left( g \right):\Delta {H_2}\\{H_2}\left( g \right) + C{l_2}\left( g \right) \mathbin{\lower.3ex\hbox{$\buildrel\textstyle\rightarrow\over{\smash{\leftarrow}\vphantom{_{\vbox to.5ex{\vss}}}}$}} 2HCl\left( g \right):\Delta {H_3}\end{array}$$
The heat of formation of $$NC{l_4}$$ in the terms of $$\Delta {H_1},\Delta {H_2},\Delta {H_3}$$ is:

A
$$\Delta {H_1} = - \Delta {H_1} + \dfrac{{\Delta {H_2}}}{2} - \dfrac{3}{2}\Delta {H_3}$$

B
$$\Delta {H_1} = \Delta {H_1} + \dfrac{{\Delta {H_2}}}{2} - \dfrac{3}{2}\Delta {H_3}$$

C
$$\Delta {H_1} = \Delta {H_1} - \dfrac{{\Delta {H_2}}}{2} + \dfrac{3}{2}\Delta {H_3}$$

D
none of these

Question 6
1 / -0

For the process Dry ice $$\rightarrow CO_2(g)$$.

A
$$\Delta H$$ is positive and $$\Delta S$$ is negative

B
Both $$\Delta H$$ and $$\Delta S$$ are negative

C
Both $$\Delta H$$ and $$\Delta S$$ are positive

D
$$\Delta H$$ is negative and $$\Delta S$$ is positive

Question 7
1 / -0

Consider the following processes:
$$\frac { 1 }{ 2 } A\longrightarrow B:\quad \quad \quad \quad \quad \triangle H=150$$
$$3B\longrightarrow 2C+D:\quad \quad \quad \quad \quad \triangle H=-125$$
$$E+A\longrightarrow 2D\quad \quad \quad \quad \quad \quad \quad \triangle =350$$
For B+D $$\rightarrow$$ E+2C,$$\triangle$$H will be:

A
325 kJ/mol

B
525 kJ/mol

C
-175 kJ/mol

D
-325 kJ/mol

Question 8
1 / -0

An ideal gas expands according to the law $$P^{2}V$$= constant. The internal energy of the gas

A
Increases continuously

B
Decreases continuously

C
Remain constant

D
First increases and then decreases

Question 9
1 / -0

Assuming that water vapour is an ideal gas, the internal energy change $$(\Delta U) $$ when $$1 mol$$ of water is vapourised at $$1 bar$$ pressure and $$100 ^ { \circ } C .$$ (Given: Molar enthalpy of vapourisation of water at $$1 bar$$ and $$373 K = 41 kJ mol ^ { -1 }$$ and $$R = 8.3 \mathrm { Jmol } ^ { - 1 } \mathrm { K } ^ { - 1 } \text { will be } )$$

A
$$4.100 \mathrm { kJ } \mathrm { mol } ^ { - 1 }$$

B
$$3.7904 \mathrm { kJ } \mathrm { mol } ^ { - 1 }$$

C
$$37.904 \mathrm { kJ } \mathrm { mol } ^ { - 1 }$$

D
$$41.00 \mathrm { kJ } \mathrm { mol } ^ { - 1 }$$

Question 10
1 / -0

For a reaction, $$A(g) \to A(l); \Delta H= -3RT$$. The correct statement for the reaction is:

A
$$\Delta H = \Delta U \neq 0$$

B
$$\Delta H = \Delta U =0$$

C
$$|\Delta H |<| \Delta U |$$

D
$$|\Delta H| > |\Delta U |$$

Submit Test

Thermodynamics ...

Question 1

1165

837

865

815

Question 2

298 K

500 K

900 K

none of the above

Question 3

$$\Delta H> T\Delta S$$

$$\Delta H< T\Delta S$$

$$\Delta H= T\Delta S$$

$$T\Delta S=0$$

Question 4

non-spontaneous at all temperature

non-spontaneous at low temperature

non-spontaneous at high temperature

spontaneous at high temperature

Question 5

$$\Delta {H_1} = - \Delta {H_1} + \dfrac{{\Delta {H_2}}}{2} - \dfrac{3}{2}\Delta {H_3}$$

$$\Delta {H_1} = \Delta {H_1} + \dfrac{{\Delta {H_2}}}{2} - \dfrac{3}{2}\Delta {H_3}$$

$$\Delta {H_1} = \Delta {H_1} - \dfrac{{\Delta {H_2}}}{2} + \dfrac{3}{2}\Delta {H_3}$$

none of these

Question 6

$$\Delta H$$ is positive and $$\Delta S$$ is negative

Both $$\Delta H$$ and $$\Delta S$$ are negative

Both $$\Delta H$$ and $$\Delta S$$ are positive

$$\Delta H$$ is negative and $$\Delta S$$ is positive

Question 7

325 kJ/mol

525 kJ/mol

-175 kJ/mol

-325 kJ/mol

Question 8

Increases continuously

Decreases continuously

Remain constant

First increases and then decreases

Question 9

$$4.100 \mathrm { kJ } \mathrm { mol } ^ { - 1 }$$

$$3.7904 \mathrm { kJ } \mathrm { mol } ^ { - 1 }$$

$$37.904 \mathrm { kJ } \mathrm { mol } ^ { - 1 }$$

$$41.00 \mathrm { kJ } \mathrm { mol } ^ { - 1 }$$

Question 10

$$\Delta H = \Delta U \neq 0$$

$$\Delta H = \Delta U =0$$

$$|\Delta H |<| \Delta U |$$

$$|\Delta H| > |\Delta U |$$

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