21.

A first-order reaction is 50% completed in 40 minutes at 300 K and in 20 minutes at 320 K. Calculate the activation energy of the reaction.

(Given: log 2 = 0.3010, log 4 = 0.6021, R = 8.314 JK^–1 mol^–1)

What happens when

A freshly prepared precipitate of Fe(OH)₃ is shaken with a small amount of FeCl₃ solution?

What happens when

Persistent dialysis of a colloidal solution is carried out?

What happens when

An emulsion is centrifuged?

For the reaction

$$\begin{gathered} 2AgCl \left(s\right) + H_2 \left(g\right) (1 atm) \stackrel{ }{\to } 2 Ag \left(s\right) + 2H^{+} (0.1 M) + 2C{l}^{-} (0.1 M), \\ ∆G^o = - 43600 J at {25}^o C \end{gathered}$$

Calculate the e.m.f. of the cell.
[log 10^–n = – n]

Define fuel cell and write its two advantages.

Give reasons:

H₃PO₃ undergoes disproportionation reaction but H₃PO₄ does not.

Give reason:

When Cl₂ reacts with an excess of F₂. ClF₃ is formed and not FCl₃

Give Reason:

Dioxygen is a gas while Sulphur is a solid at room temperature.

Draw the structures of the following.
(i) XeF₄
(ii) HClO₃