Difference between Internal Energy and Enthalpy

Q. The enthalpy of formation of methane at constant pressure and 300 K is – 78.84 KJ. The enthalpy of formation at constant volume is:

1. – 54.0 kJ
2. – 75.5 kJ
3. – 102.6 kJ
4. + 75.5 kJ

Q.

ASSERTION(A): For every chemical reaction at equilibrium, standard Gibbs energy of the reaction is zero.
REASON(R): At constant temperature and pressure, chemical reactions are spontaneous in the direction of the decreasing Gibbs energy.

1. If both (A) and (R) are correct, and (R) is the correct explanation for (A)

2. If the both (A) and (R) are correct, but (R) is not the correct explanation for (A)

3. If (A) is correct, but (R) is incorrect

4. IF (A) is incorrect, but (R) is correct

Q. The difference between heats of reaction at constant pressure and at constant volume for the reaction $2C_6{H}_6\left(l\right)+15O_2\left(g\right)\to 12C{O}_2\left(g\right)+6H_{2}O\left(l\right)at{25}^{\circ }C$ at in kJ is

1. –7.43
2. + 3.72
3. –3.72
4. + 7.43

Q. A calorimeter contains ice. The energy of 500 calories is required, to heat the system from270 K to 272 K and energy of 16600 calories isrequired to heat that system from 272 K to 274 K.The heat capacity is defined as the product ofmass of the object and its specific heat. The specific heat of ice is 0.5 cal/gram-K. The heat capacity of calorimeter is (1)150 cal/K (2)100 cal/K (3)120 cal/K (4)180 cal/K

Q. Write chemical equation of combustion reaction for Hexyne.

Q. For the combustion of 1 mole of a liquid benzene at ${25}^{o}C$, the enthalpy is given by:
$C_6{H}_6\left(l\right)+\frac{15}{2}{O}_2\left(g\right)\to 6C{O}_2\left(g\right)+3H_{2}O\left(l\right)$ $\Delta H=-780980$ cal
What would be the internal energy of the reaction?

1. $-780kcal$
2. $780kcal$
3. $-580kcal$
4. $580kcal$

Q. Write chemical equations of combustion reaction for Pentene

Q.

When $1.0g$ of oxalic acid ($H_2{C}_2{O}_4)$ is burned in a bomb calorimeter whose heat capacity is $8.75kJ/K$, the temperature increased by $0.312K$. The enthalpy of combustion of oxalic acid at ${27}^{\circ }C$.

1. -244.452 kJ/mol

2. 241.95 kJ/mol

3. -58.85 kJ/mol

4. -245.7 kJ/mol

Q. For the reaction $N_2+3H_2\rightleftharpoons 2N{H}_3;\Delta H=$

1. $\Delta E-RT$
2. $\Delta E-2RT$
3. $\Delta E+RT$
4. $\Delta E+2RT$

Q. For the reaction, $C_{\left(s\right)}+O_{2\left(g\right)}\to C{O}_{2\left(g\right)}$

1. $\Delta H$>$\Delta U$
2. $\Delta H$<$\Delta U$
3. $\Delta H$=$\Delta U$
4. Cannot be predicted

Q. If a gas absorbs $200J$ of heat and expands by $500c{m}^3$ against a constant pressure of $2\times {10}^{5}N{m}^{-2}$, then the change in internal energy is:

1. -300
2. -100
3. 300
4. 100

Q. The enthalpy of formation of methane at constant pressure and 300 K is – 78.84 KJ. The enthalpy of formation at constant volume is:

1. – 75.5 kJ
2. – 102.6 kJ
3. + 75.5 kJ
4. – 54.0 kJ

Q. For complete combustion of ethanol,
$C_2{H}_{5}OH\left(l\right)+3O_2\left(g\right)\to 2C{O}_2\left(g\right)+3H_{2}O\left(l\right),$
the amount of heat produced as measured in bomb calorimeter, is 1364.47 kJ $mo{l}^{-1}at{25}^{o}C.$ Assuming ideality the enthalpy of combustion, ${△}_{C}H,$ for the reaction will be:
(R = 8.314 kJ mol^{-1})

1. -1460.50 kJ $mo{l}^{-1}$
2. -1350.50 kJ $mo{l}^{-1}$
3. -1366.95 kJ $mo{l}^{-1}$
4. -1361.95 kJ $mo{l}^{-1}$

Q. Write chemical equation of combustion reaction for Butane.

Q. an isochoric reversible process

1. $\Delta U=19.90kJ,\Delta H=24.058kJ;w=0$
2. $\Delta U=19.90kJ,\Delta H=-24.058kJ;w=0$
3. None of these
4. $\Delta U=-19.90kJ,\Delta H=24.058kJ;w=0$

Q. Write chemical equation of combustion reaction for Toluene.

Q. A mixture of two moles of carbon monoxide and one mole of oxygen, in a closed vessel is ignited to convert the carbon monoxide to carbon dioxide. If $\Delta H$ is the enthalpy change and $\Delta E$is the change in internal energy, then

1. $\Delta H>\Delta E$
2. $\Delta H<\Delta E$
3. $\Delta H=\Delta E$

4. The relationship depends on the capacity of the vessel

Q. A surveyor's $30m$ steel tape is correct at a temperature of ${20}^{o}C$. The distance between two points, as measured by this tape on a day when the temperature is ${35}^{o}C$, is 26 m. What is the true distance between the points ?
$({\alpha }_{steel}=1.2\times {10}^{-5}{/}^{o}C)$

1. $26.00476$ m
2. $27.00468$ m
3. $25.6658$ m
4. none of these

Q. For the combustion of $C_6{H}_{10}$ with the required amount of oxygen, which of the following is correct? (Where reactants and products are in their standard states)

1. $\Delta H>\Delta E$
2. $\Delta H=\Delta E$
3. $\Delta H<\Delta E$
4. None of these

Q.

For the reaction $A{g}_{2}O\left(s\right)\to 2Ag\left(s\right)+\frac{1}{2}{O}_2\left(g\right)$ which one of the following is true?

1. 

2. 

3. 

4. 

Q. If agas absorbs $200J$ of heat and expands by $500c{m}^3$ against a constant pressure of $2\times {10}^{5}N{m}^{-2}$, then the change in internal energy is

1. $-300$
2. $+300$
3. $+100$
4. $-100$

Q.

A gas expands from 1.5 to 6.5 L against a constant pressure of 0.5 atm and during this process the gas also absorbs 100 J of heat. The change in the internal energy of the gas is:

1. $-153.3$ J
2. $153.3$ J
3. $353.3$ J
4. $-353.3$ J

Q. In a thermodynamic process the pressure of fixed mass of gas is changed. In this process gas releases 20 J heat and 8 J work is done on the gas. If initial internal enrgy of the gas is 30 J, then final internal energy is:

1. 2 J
2. 58 J
3. 42 J
4. 18 J

Q. For the combustion of $C_6{H}_{10}$ with the required amount of oxygen, which of the following is correct? (Where reactants and products are in their standard states)

1. $\Delta H>\Delta E$
2. $\Delta H=\Delta E$
3. $\Delta H<\Delta E$
4. None of these

Q. What is the heat added to the gas in process $b\to c$ ?

1. $-\frac{9}{8}{p}_0{V}_0$
2. $\frac{3}{2}{p}_0{V}_0$
3. $\frac{9}{8}{p}_0{V}_0$
4. 0

Q.

For the reaction at ${25}^{\circ }C{N}_2{O}_{4\left(g\right)}\rightleftharpoons 2N{O}_{2\left(g\right)}$, if $\Delta G_f^{\circ }$ for $N_2{O}_4$ and $N{O}_2$ are 23.49 and 12.39 $KCal.mo{l}^{-1}$, then $log\left(K_p\right)$ for the reaction is:

1. -113.332

2. -113.332

3. -113.332

4. -0.9393

Q. One mole of non-ideal gas undergoes a change of state (1.0 atm, 3.0 L, 200 K) to (4.0 atm, 5.0 L, 250 K) with a change in internal energy $\Delta U$ = 40 L-atm. The change in enthalpy of the process in L-atm is :

1. 43
2. 57
3. 42
4. None of these

Q. The latent hear of vaporization of water is $2240J$. If the work done in the process of vaporization of $1g$ is $168J$, then increase in internal energy is:

1. $1940J$
2. $2408J$
3. $2240J$
4. $2072J$

Q. Which is not the correct relation between enthalpy $\Delta H$ and intrinsic energy $\Delta E$

1. $\Delta H=\Delta E+P\Delta V$
2. $\Delta H=\Delta E+nRT$
3. $\Delta H=\Delta E-P\Delta V$
4. $\Delta E=\Delta H-P\Delta V$

Q.

$(\Delta H-\Delta U)$ for the formation of carbon monoxide ($CO$) from its elements at $298K$ is ( $R=8.314J{K}^{-1}mo{l}^{-1}$)

1. $-2477.57Jmo{l}^{-1}$

2. $2477.57Jmo{l}^{-1}$

3. $-1238.78Jmo{l}^{-1}$

4. $1238.78Jmo{l}^{-1}$