Enthalpy of Neutralisation

Q.

State the Arrhenius concept of acids and bases and discuss the limitations.

Q. The heats of neutralization of four acids A, B, C, D are $-13.7,-9.4,-11.2,-12.4kcal$ respectively, when they are neutrelized by a common base. The acidic character obeys the order :

1. A>B>C>D
2. D>B>C>A
3. D>C>B>A
4. A>D>C>B

Q.

Is $\mathrm{NaCl}$ it An Acid or Base?

Q. When $400mL$ of $0.2M{H}_{2}S{O}_4$ solution is mixed with $600mL$ of $0.1MNaOH$solution, the increase in temperature of the final solution is $x\times {10}^{-2}K$
The value of x (Round off to the Nearest Integer) is
[Use :$H^{+}\left(aq\right)+O{H}^{-}\left(aq\right)\to H_{2}O:{\Delta }_{\gamma }H=-57.1{\text{kJ mol}}^{-1}$
$\text{Specific heat of}{H}_{2}O=4.18{\text{J k}}^{-1}{g}^{-1}$
$\text{Density of}{H}_{2}O=1.0{\text{g cm}}^{-3}$
[ Assume no change in volume of solution on mixing.]

Q. The heat of neutralization of HCl by NaOH is -55.9 kJ mol${}^{-1}$. If the heat of neutralization of HCN by NaOH is -12.1 kJ/mol, the energy of dissociation of HCN is:

1. 68 kJ
2. -43.8 kJ
3. 43.8 kJ
4. -68 kJ

Q.

Which of the following is(are) true when $\mathrm{HCl}$ (g) is passed through water? (i) It does not ionize in the solution as it is a covalent compound. (ii) It ionizes in the solution (iii) It gives both hydrogen and hydroxyl ions in the solution (iv) It forms hydronium ion in the solution due to the combination of hydrogen ion with a water molecule

1. (i) only

2. (iii) only

3. (ii) and (iv)

4. (iii) and (iv)

Q. The standard enthalpy of formation of octane $\left(C_8{H}_{18}\right)$ is $-250\text{kJ/mol}$. Calculate the enthalpy of combustion of $C_8{H}_{18}$. Given that enthalpy of formation of $C{O}_2\left(g\right)$ and $H_{2}O\left(l\right)$ are $-394\text{kJ/mol}$ and $-286\text{kJ/mol}$ respectively.

1. $-5200\text{kJ/mol}$
2. $-5726\text{kJ/mol}$
3. $-5476\text{kJ/mol}$
4. $-5310\text{kJ/mol}$

Q. Enthalpy of neutralization of $H_{3}P{O}_3$ acid is -106.68 kJ/mol using $NaOH$. If enthalpy of neutralization of $HCl$ by $NaOH$ is -55.84 kJ/mol.
Calculate $△H_{ionization}of{H}_{3}P{O}_3$ into its ions:

1. 5 kJ/mol
2. 2.5 kJ/mol
3. 50.84 kJ/mol
4. None of these

Q.

Which one of the following is an acidic salt?

1. $\mathrm{NaCl}$

2. ${\mathrm{NH}}_4\mathrm{Cl}$

3. ${\mathrm{NaHCO}}_3$

4. ${\mathrm{Na}}_2{\mathrm{CO}}_3$

Q. Equivalent weight of $N{H}_3$ in the change $N_2\Rightarrow N{H}_3$ is

1. $17$
   
2. $\frac{17}{2}$
   
3. $\frac{17}{3}$
4. $\frac{17}{6}$
   

Q.

Why is aqueous solution of alum acidic?

Q. The enthalpy of neutralization of a weak monoprotic acid ($HA$) in $1M$ solution with a strong base is $-55.95kJ/mol.$ If the unionized acid requires $1.4kJ/mol$ heat for its complete ionization and enthalpy of neutralization of the strong monobasic acid with a strong monoacidic base is $-57.3kJ/mol.$ What is the % ionization of the weak acid in molar solution?

1. 3.57%
2. 35.7%
3. 10%
4. 1.5%

Q. 10 mL of $H_2{O}_2$ solution on treatment with KI and titration of liberated $I_2$, required 10 mL of 1N hypo. Thus $H_2{O}_2$ is -

1. $Allarecorrect$
2. $1N$
3. $5.6volume$
4. $17g{L}^{-1}$

Q. Enthalpy of neutralization of a strong acid with a strong base is 13.7 kcal. When an unknown acid (1 eq) is neutralized with (1 eq) strong base, the enthalpy change is 10.7 kcal which of the following statements is/are correct regarding the unknown acid?

1. Unknown acid is a strong acid
2. Unknown acid is a weak acid
3. 3.0 kcal heat utilised to dissociate the unknown acid
4. 10.7 kcal heat utilised to dissociate unknown acid

Q.

Which of the following phenomena occur when a small amount of acid is added to water?

1. Dilution

2. Ionization

3. Neutralization

4. Both (A) and (B)

Q.

Which of the following acid will release maximum amount of heat when completely neutralized by strong base NaOH?

1. 1M HCl

2. 1M HNO₃

3. 1M HClO₄

4. 1M H₂SO₄

Q. Heat of neutralization of acetic acid and. sodium hydroxide is

1. < 57.1 kJ/eq
2. > 57.1 kJ/eq
3. Cannot be predicted
4. = 57.1 kJ/eq

Q. Calculate the enthalpy change when $50mL$ of $0.01M$ $Ca(OH{)}_2$ reacts with $25mL$ of $0.01M$ $HCl$. Given that $\Delta H^o$ of neutralization of a strong acid and a strong base is $14kcalmo{l}^{-1}$

1. $6.4cal$
2. $3.5cal$
3. $1.4cal$
4. $9.4cal$

Q.

The coagulation of 200 mL of a positive colloid took place when $0.73\mathrm{g}$ of $\mathrm{HCl}$ was added to it without changing the volume much. The flocculation value of $\mathrm{HCl}$ for the colloid is:

1. $100\mathrm{m}\mathrm{mol}$

2. $36.5\mathrm{m}\mathrm{mol}$

3. $0.365\mathrm{m}\mathrm{mol}$

4. $150\mathrm{m}\mathrm{mol}$

Q. Enthalpy of neutralization of HCl with NaOH is x. The heat evolved when 500 ml of 2N HCl is mixed with 250 ml of 4N NaOH will be

1. 10 x
2. 500 x
3. x
4. 100 x

Q. 100 ml of 0.3 M HCI solution is mixed with 100 ml of 0.33 M KOH solution. The amount of heat liberated is:
Consider,
$△H_{neut}=-55.2kJmo{l}^{-1}$

1. 1.66 kJ
2. 1.42 kJ
3. 1.31 kJ
4. 1.94 kJ

Q. In which of the following cases of mixing of a strong acid and a strong base each of 1 N concentration would the temperature increase of the solution be the same (assume heat evolved in neutralisation is only used up to increase the temperature of the solution)?

1. 20 mL acid and 30 mL alkali
2. 10 mL acid and 10 mL alkali
3. 35 mL add and 15 mL alkali
4. 50 mL acid and 50 mL alkali

Q.

How are salts classified? Describe giving one example of each.

Q. One mole of each methonoic acid and sodium hydroxide are mixed. If x is the heat released during formation of water from $H^{+}$ and $O{H}^{-}$, the heat evolved in the above neutralization is:

1. Less than x
2. Twice that of x
3. More than x
4. Equal to x

Q. 30.An aqueous solution of an acid is so weak that it can be assumed to be practically unionized when boiled at 100.4 degree Celsius. 25 ml of the solution was neutralized by 38.5 ml of 1 N solution of NaOH. What is the basicity of acid if Kb for water is 0.52 K Kg/mol?

Q. Heat of neutralisation for the given reaction $NaOH+HCl\to NaCl+H_{2}O$ is $57.9kJ/mole$. What will be the heat released when 0.75 moles of $NaOH$ is titrated against 1.25 moles of $HCl$?

1. $47.12$ kJ
2. $43.42$ kJ
3. $28.65$ kJ
4. $22.56$ kJ

Q. Heat of neutralization of NaOH and HCl is -57.46 kJ/equivalent. The heat of ionisation of water in kJ/mol is:

1. -57.46
2. 114.92
3. 57.46
4. -114.92

Q. Enthalpy of neutralization of HCl by NaOH is -55.84 kJ/mol and by $N{H}_{4}OH$ is -51.34 kJ/mol. The enthalpy of ionization of $N{H}_{4}OH$ is :

1. -107.18 kJ
2. +107.18 kJ
3. +4.5 kJ
4. -4.5 kJ

Q.

Do you expect different products in solution when aluminium (III) chloride and potassium chloride treated separately with (i) normal water (ii) acidified water, and (iii) alkaline water? Write equations wherever necessary.

Q. The enthalpy of neutralisation of strong acid by a strong base is $-57.32kJmo{l}^{-1}$. The enthalpy of formation of water is $-285.84kJmo{l}^{-1}$. The enthalpy of formation of hydroxyl ion is :

1. $+228.52kJmo{l}^{-1}$
2. $-114.26kJmo{l}^{-1}$
3. $-228.52kJmo{l}^{-1}$
4. $+114.2kJmo{l}^{-1}$