29 - Chemical and Ionic Equilibrium Questions Answers

HCN ------------------->  H⁺ + CN^-

0.1                                 0          0

0.1-x                              x           x

pH = 5.2

so -log[H⁺] = 5.2 

solve for [H⁺], it will give x

then calculate K_a

mili eq of acid = VN = 20*0.1 = 2

mili eq of base = VN = 5*0.45 = 2.25

total milieq = 2.25-2 = 0.25 of base in 25 ml

so N = 0.25/25 = 10-2

so pOH = 2 so pH = 12

     A + 3B


--------->


2C + D

     1    1/2                0     0

    1-x   1/2-3x          2x    x

according to the given condition 1/2 - 3x = 2x

                                        so 1/10 = x

so 3x = 3/10

so % = 0.3*100/0.5 = 60

CaCO₃     ---------->   CaO   +   CO₂ (g)

0.2 mole                   0            0

0.06                       0.14       0.14

so K_p= p                       only CO₂ is gas so its pressure is considered 

now p = 0.14*0.0821*1073/10 

now solve

boiling point elevation = (-32.7) - (-33.4) = 0.7

now according to the given data 

boiling point elevation = 1000*K(ammonia)*1/1 = 1000*0.00035 = 0.35

so i = 0.7/0.35 = 2

so 100 % dissociation

If we multiply mole fraction to pressure, we get the pressure exerted by the component so it is a good way to get answer. and 1 represents net sum of mole fractions of all the components. here first and second 1/6 stands for mole fraction of ethane and carbon monooxide. 

At equilibrium mole fraction of CO = 1/6, that of CH₃CH₃ = 1/6

so mole fraction of CH₃COCH₃  = 1- 1/6 - 1/6 = 2/3

let the total pressure at equilibrium = p

so pressure of CH₃CH₃ and CO will be p/6 and p/6

and that of CH₃COCH₃ = 2p/3 

now consider the following dissociation data

CH₃COCH₃ ----> CH₃CH₃ + CO

300 mm                        0                      0                            at starting

300-x  mm                    x                       x                            at  equilibrium 

here x = p/6  (1)  and 300-x = 2p/3   (2)                                         add these equations and get the value of p

YES

very soon

Dissociation is the reaction in which two or more than two product molecules are formed.

ex.                  PCl₅   --->     PCl₃  +  Cl₂

whereas ionisation is the reaction in which ions are formed 

ex.               MgCl₂  ---->    Mg⁺⁺   +  2 Cl^-