(i) According to Le Chatelier’s principle, the equilibrium will shift in the backward direction.
(ii) According to Le Chatelier’s principle, as the reaction is endothermic, the equilibrium will shift in the forward direction.
(iii) The equilibrium of the reaction is not affected by the presence of a catalyst. A catalyst only increases the rate of a reaction. Thus, equilibrium will be attained quickly.

pH of tomato juice = 4.2
\(\log { \left[ { H }^{ + } \right] } =-4.2=\bar { 5 } .80\)
\( \left[ { H }^{ + } \right] =antilog \ \bar { 5 } .80=6.310\times { 10 }^{ -5 }\)

(a) Human muscle fluid 6.83:
pH=6.83
pH=–log[H⁺]
∴6.83=–log[H⁺][H+]=1.48×10⁻⁷M


(b) Human stomach fluid, 1.2:
pH=1.2
1.2=–log[H⁺]
∴[H⁺]=0.063


(c) Human blood, 7.38:
pH=7.38=−log[H+]
∴[H⁺]=4.17×10⁻⁸M


(d) Human saliva, 6.4:
pH=6.4
6.4 =–log[H⁺]
[H+]=3.98×10⁻⁷

2.42 x 10^-4

Calculation of K_p 
PCl₅(g) ⇌ PCl₃(g) + Cl₂ (g)
     1             0               0
    (1- α)       α              α
Total no. of moles in the equilibrium mixture = 1 - α + α + α
= (1 + α) mol.
Let the total pressure of equilibrium mixture = p atm
Partial pressure of PCl₅
\(p_{ { PCI }_{ 5 } }\ =\ \frac { 1-\alpha }{ 1+\alpha } \times p\ atm\)
Partial pressure of PCI₃ = \(\ \frac { \alpha }{ 1+\alpha } \times p\ atm\)
Partial pressure of CI₂
\(p_{ { CI }_{ 2 } }\ =\ \frac { \alpha }{ 1+\alpha } \times p\ atm\)
K_p = \(\frac { { p }_{ { PCI }_{ 3 } }\times { p }_{ { CI }_{ 2 } } }{ { p }_{ PCI_{ s } } } \)
= \(\frac { \left( \frac { \alpha }{ 1+\alpha } p\ atm \right) \left( \frac { \alpha }{ 1+\alpha } p\ atm \right) }{ \frac { 1-\alpha }{ 1+\alpha } p\ atm } =\frac { { \alpha }^{ 2 }p }{ 1-\alpha ^{ 2 } } atm\)
P = 4 atm and α = 10% = \(\frac { 10 }{ 100 } \) = 0.1
K_p = \(\frac { (0.1)\times (0.1)\times (4\ atm) }{ 1-(0.1{ ) }^{ 2 } } \)
= \(\frac { 0.04 }{ 0.99 } \) = 0.04 atm.
Calculation of P under new condition
α = 0.2, K_p = 0.04 atm
K_p = \(\frac { { \alpha }^{ 2 }p }{ 1-\alpha ^{ 2 } } \)or \(\frac { { K_{ p }(1-\alpha }^{ 2 }) }{ \alpha ^{ 2 } } \)
= \(\frac { (0.04atm)[(1-(0.2)^{ 2 }] }{ (0.2{ ) }^{ 2 } } \)
= \(\frac { 0.04atm\times 0.96 }{ 0.04 } \)
= 0.96 atm.

(a) For the given reaction,

 

(b) (i) According to Le Chatelier’s principle, the equilibrium will shift in the backward direction.
(ii) According to Le Chatelier’s principle, as the reaction is endothermic, the equilibrium will shift in the forward direction.
(iii) The equilibrium of the reaction is not affected by the presence of a catalyst. A catalyst only increases the rate of a reaction. Thus, equilibrium will be attained quickly.

\({ N }_{ 2 }\left( g \right) +3{ H }_{ 2 }\left( g \right) \rightleftharpoons 2{ NH }_{ 3 }\left( g \right) \triangle H=192.38 \ KJ \ { mol }^{ -1 }\)It is an exothermic process as \(\triangle H\) is negative.
Effect of temperature According to Le-Chatelier's principle, low temperature is favourable for high yield of ammonia, but practically very low temperature slow down the reaction. So, optimum temperature 700 K is favourable in attainment of equilibrium.
Effect of pressure  Similarly, high pressure about 200 atm is favourable for high yield of ammonia. On increasing pressure, reaction goes in the forward direction because the number of moles decreases in the forward direction.
Addition of argon At constant volume addition of argon does not affect the equilibrium because it does not change the partial pressure of the reactants or products incolved in the reaction and the equilibrium remains undisturbed.

\(pH={ pK }^{ a }+\log { \frac { \left[ Salt \right] }{ \left[ Acid \right] } } =-\log { \left( 1.75\times { 10 }^{ -5 } \right) } +\log { \frac { 0.15 }{ 0.10 } } \quad \)
= (5 - 0.2430) + 0.1761 =4.757 + 0.1761 = 4.933
1 cc of 1 M NaOH contains NaOH = 10^-3 mol. This will convent 10^-3 mol of acetic acid into the salt so that salt formed = 10^-3 mol.
Now, [Acid] = 0.10 - 0.001 = 0.099 M
[Salt]  = 0.15 + 0.001 = 0.151 M
pH = 4.757 + \(\log { \frac { 0.151 }{ 0.099 } } \)
= 4.757 + 0.183 =4.940
Increase in pH = 4.940 - 4.933 = 0.007 which is negligible.

When catalyst is added, the state of equilibrium is not distributed but equilibrium is attained quickly. This is because the catalyst increases the rate of forward and backward reaction to the same extent.