EASY

Earn 100

The enthalpy of neutralisation of $H C O_{3}^{-} (a q)$ with strong alkali is $- 42 k J / m o l e$ and enthalpy of neutralisation of strong acid with strong alkali is $- 56 k J / e q u i v$ . Therefore, enthalpy of dissociation of $H C O_{3}^{-} (a q)$ is-

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Important Questions on Chemical Thermodynamics and Energetics

MEDIUM

Chemistry>Physical Chemistry>Chemical Thermodynamics and Energetics>Enthalpy

A process has

Δ H = 200 J m o l^{- 1}

and

Δ S = 40 J K^{- 1} m o l^{- 1} .

Out of the values given below choose the minimum temperature above which the process will be spontaneous:

HARD

Chemistry>Physical Chemistry>Chemical Thermodynamics and Energetics>Enthalpy

When

600 mL

0.2 M {HNO}_{3}

is mixed with

400 mL

0.1 M NaOH

solution in a flask, the rise in temperature of the flask is_____

\times 10^{- 2} ° C

(Enthalpy of neutralisation

= 57 kJ {mol}^{- 1}

and Specific heat of water

= 4.2 {JK}^{- 1} g^{- 1}

) (Neglect heat capacity of flask)

EASY

Chemistry>Physical Chemistry>Chemical Thermodynamics and Energetics>Enthalpy

The correct thermodynamic conditions for the spontaneous reaction at all temperatures is:

MEDIUM

Chemistry>Physical Chemistry>Chemical Thermodynamics and Energetics>Enthalpy

Given:

(i)

C (graphite) + O_{2} (g) \to {CO}_{2} (g);

{ΔrH}^{Θ} = x kJ {mol}^{- 1}

(ii)

C (graphite) + \frac{1}{2} O_{2} (g) \to CO (g);

{ΔrH}^{Θ} = y kJ {mol}^{- 1}

(iii) CO (g) + \frac{1}{2} O_{2} (g) \to {CO}_{2} (g);

{ΔrH}^{Θ} = z kJ {mol}^{- 1}

Based on the above thermochemical equations, find out which one of the following algebraic relationships is correct?

MEDIUM

Chemistry>Physical Chemistry>Chemical Thermodynamics and Energetics>Enthalpy

The heat of neutralization of the following reaction is $- 57.1 kJ {mol}^{- 1}$ .

$NaOH (aq) + HCl (aq) \to NaCl (aq) + H_{2} O (l)$

Which one of the following processes is mainly responsible for the heat released?

MEDIUM

Chemistry>Physical Chemistry>Chemical Thermodynamics and Energetics>Enthalpy

The process with negative entropy change is:

HARD

Chemistry>Physical Chemistry>Chemical Thermodynamics and Energetics>Enthalpy

One mole of an ideal gas at

300 K

in thermal contact with its surroundings expands isothermally from

1.0 L

2.0 L

against a constant pressure of

3.0 atm

. In this process, the change in entropy of the surroundings

(∆ S_{s u r r})

J K^{- 1}

is:

(1 L atm = 101.3 J)

MEDIUM

Chemistry>Physical Chemistry>Chemical Thermodynamics and Energetics>Enthalpy

For which of the following processes,

∆ S

is negative?

MEDIUM

Chemistry>Physical Chemistry>Chemical Thermodynamics and Energetics>Enthalpy

Equal volume of

1 M HCl

and

1 M H_{2} {SO}_{4}

are neutralised by dil.

NaOH

solution separately. If

X Kcal

and

Y Kcal

of heat are liberated respectively, then which of the following relation is correct?

EASY

Chemistry>Physical Chemistry>Chemical Thermodynamics and Energetics>Enthalpy

The heat of neutralisation of hydrogen cyanide

(HCN)

- 2 .9 kcal {mol}^{- 1}

. This shows that heat of dissociation of

HCN

EASY

Chemistry>Physical Chemistry>Chemical Thermodynamics and Energetics>Enthalpy

The heat of combustion of carbon to

C O_{2}

- 393.5 kJ / mol

. The heat released upon the formation of

35.2 g

C O_{2}

from carbon and oxygen gas is

EASY

Chemistry>Physical Chemistry>Chemical Thermodynamics and Energetics>Enthalpy

When $400 mL$ of $0.2 M H_{2} {SO}_{4}$ solution is mixed with $600 mL$ of $0.1 MNaOH$ solution, the increase in temperature of the final solution is $— \times 10^{- 2} K$ . (Round off to the nearest integer).

[Use : $H^{+} (aq) + {OH}^{-} (aq) \to H_{2} O :$ $Δ_{γ} H = - 57.1 kJ {mol}^{- 1}]$

Specific heat of $H_{2} O = 4.18 J K^{- 1} g^{- 1}$ , density of $H_{2} O = 1.0 g {cm}^{- 3}$

Assume no change in volume of solution on mixing.

HARD

Chemistry>Physical Chemistry>Chemical Thermodynamics and Energetics>Enthalpy

The heat of atomization of methane and ethane are

360 kJ {mol}^{- 1}

and

620 kJ {mol}^{- 1}

, respectively. The longest wavelength of light capable of breaking the

C - C

bond is (Avogadro's number

= 6.023 \times 10^{23}, h = 6.62 \times 10^{- 34} J s

)

HARD

Chemistry>Physical Chemistry>Chemical Thermodynamics and Energetics>Enthalpy

The entropy change associated with the conversion of

1 k g

of ice at

273 K

to water vapours at

383 K

is:

(Specific heat of water liquid and water vapour are

4.2 k J K^{-}

and

2.0 k J K^{- 1} k g^{- 1}

; heat of liquid fusion and vaporization of water are

334 k J k g^{- 1}

and

2491 k J k g^{- 1}

, respectively). (

l o g

273 = 2.436, \log 373 = 2.572, \log 383 = 2.583

)

EASY

Chemistry>Physical Chemistry>Chemical Thermodynamics and Energetics>Enthalpy

For a sample of perfect gas, when its pressure is changed isothermally from

p_{i}

p_{f}

, the entropy change is given by

EASY

Chemistry>Physical Chemistry>Chemical Thermodynamics and Energetics>Enthalpy

Identify the INVALID equation.

HARD

Chemistry>Physical Chemistry>Chemical Thermodynamics and Energetics>Enthalpy

Given:

C (graphite) + O_{2} (g) \to {CO}_{2} (g); Δ_{r} H^{o} = - 393 .5 kJ {mol}^{- 1}

H_{2} (g) + \frac{1}{2} O_{2} (g) \to H_{2} O (l); Δ_{r} H^{o} = - 285 .8 kJ {mol}^{- 1}

{CO}_{2} (g) + 2 H_{2} O (l) \to {CH}_{4} (g) + 2 O_{2} (g); Δ_{r} H^{o} = + 890 .3 kJ {mol}^{- 1}

Based on the above thermochemical equations, the value of

Δ_{r} H^{o}

298 K

for the reaction

C (graphite) + 2 H_{2} (g) \to {CH}_{4} (g)

will be:

MEDIUM

Chemistry>Physical Chemistry>Chemical Thermodynamics and Energetics>Enthalpy

While performing a thermodynamics experiment, a student made the following observations, $HCl + NaOH \to NaCl + H_{2} O Δ H = - 57.3 kJ {mol}^{- 1}$

${CH}_{3} COOH + NaOH \to {CH}_{3} COONa + H_{2} O$

$ΔH = - 55.3 kJ {mol}^{- 1}$ .

The enthalpy of ionization of ${CH}_{3} COOH$ as calculated by the student is $kJ {mol}^{- 1}$ .

MEDIUM

Chemistry>Physical Chemistry>Chemical Thermodynamics and Energetics>Enthalpy

The heat of neutralisation will be highest in

HARD

Chemistry>Physical Chemistry>Chemical Thermodynamics and Energetics>Enthalpy

When 100 mL of 1.0 M HCl was mixed with 100 mL of 1.0 M NaOH in an insulated beaker at constant pressure, a temperature increase of

{5.7}^{o} C

was measured for the beaker and its contents (Expt.1). Because the enthalpy of neutralization of a strong acid with a strong base is a constant

(- 57.0 k J m o l^{- 1})

, this experiment could be used to measure the calorimeter constant. In a second experiment (Expt. 2), 100 mL of 2.0 M acetic acid

(K_{a} = 2.0 \times 10^{- 5})

was mixed with 100 mL of 1.0 M NaOH (under identical conditions to Expt. 1) where a temperature rise of

{5.6}^{o} C

was measured. (Consider heat capacity of all solutions as

4.2 J g^{- 1} K^{- 1}

and density of all solutions as

1.0 g m L^{- 1}

)

Enthalpy of dissociation

(i n k J m o l^{- 1})

of acetic acid obtained from the Expt. 2 is

The enthalpy of neutralisation of HCO3-aq with strong alkali is - 42 kJ/mole and enthalpy of neutralisation of strong acid with strong alkali is- 56 kJ/equiv. Therefore, enthalpy of dissociation of HCO3-aq is-

Important Questions on Chemical Thermodynamics and Energetics

Learn and Prepare for any exam you want !

The enthalpy of neutralisation of $H C O_{3}^{-} (a q)$ with strong alkali is $- 42 k J / m o l e$ and enthalpy of neutralisation of strong acid with strong alkali is $- 56 k J / e q u i v$ . Therefore, enthalpy of dissociation of $H C O_{3}^{-} (a q)$ is-