For the reaction A + B → C + D, the initial rate for different reactions and initial concentration of reactants are given below: S.No Initial concentration Initial rate A mol L - 1 B mol L - 1 mol L - 1 s - 1 1 1 . 0 1 . 0 2 × 10 - 3 2 2 . 0 1 . 0 4 × 10 - 3 3 4 . 0 1 . 0 8 × 10 - 3 4 1 . 0 2 . 0 2 × 10 - 3 5 1 . 0 4 . 0 2 × 10 - 3 Write the rate law equation.

For the given reaction, rate = k [ A ] x [ B ] y . After substituting the values of initial rates and initial concentrations, the value of x and y can be calculated. Then ( x + y ) will give the order of the reaction. For experiment ( i ) 2 . 0 × 10 - 3 = [ 1 . 0 ] x [ 1 . 0 ] y For experiment ( ii ) 4 . 0 × 10 - 3 = [ 2 . 0 ] x [ 1 . 0 ] y For experiment ( iii ) 8 . 0 × 10 - 3 = [ 4 . 0 ] x [ 1 . 0 ] y For experiment ( iv ) 2 . 0 × 10 - 3 = [ 1 . 0 ] x [ 2 . 0 ] y For experiment ( v ) 2 . 0 × 10 - 3 = [ 1 . 0 ] x [ 4 . 0 ] y Determination of x . In order to get the value of x , divide equation (2) by (1) 4 . 0 × 10 - 3 2 . 0 × 10 − 3 = [ 2 . 0 ] x [ 1 . 0 ] y [ 1 . 0 ] x [ 1 . 0 ] y 2 1 = 2 x x = 1 Determination of y . In order to get the value of y , divide equation (4) by (1) 2 . 0 × 10 - 3 2 . 0 × 10 - 3 = [ 1 . 0 ] x [ 2 . 0 ] y [ 1 . 0 ] x [ 1 . 0 ] y y = 0 The overall order of reaction = 1 + 0 = 1 The rate law (also known as the rate equation) for a chemical reaction is an expression that provides a relationship between the rate of the reaction and the concentrations of the reactants participating in it. Rate law, r α A 1 B 0 r α A 1 r = k A 1

When a coordination compound CoCl 3 . 6 NH 3 is mixed with AgNO 3 , three moles of AgCl are precipitated per mole of the compound. Write the structural formula and IUPAC name of the coordination compound.

When a coordination compound CoCl 3 . 6 NH 3 is mixed with AgNO 3 moles of AgCl are precipitated per mole of the compound. This indicates that in the coordination compound, all the three chlorine atoms are in the ionisation sphere and six ammonia molecules are in the coordination sphere. Structural formula of the complex is [ Co ( NH 3 ) 6 ] Cl 3 . and IUPAC name of the complex is hexamminecobalt (III) chloride.

Show that for a first order reaction the time required to complete 75 % of reaction is about 2 times more than that required to complete 50 % of the reaction.

The relationship between the time taken and the rate constant of the reaction is given as, t = 2 . 303 k log a a - x . For the first order reaction, time required to complete 50 % of the reaction is, t = 2 . 303 k log a a - x ⇒ t 50 % = 2 . 303 k log 100 100 - 50 . t 50 % = 2 . 303 k log 100 50 ⇒ t 50 % = 2 . 303 k log 2 . For the first order reaction, time required to complete 75 % of the reaction is, t = 2 . 303 k log a a - x ⇒ t 75 % = 2 . 303 k log 100 100 - 75 . t 75 % = 2 . 303 k log 100 25 ⇒ t 75 % = 2 . 303 k log 4 . t 75 % = 2 . 303 k log 2 2 ⇒ t 75 % = 2 × 2 . 303 k log 2 . t 75 % = 2 × t 50 % . Thus, it will be twice the time taken for 50 % of the reaction.

Using the valence bond approach, predict the shape, hybridisation and magnetic behaviour of [ Ni ( CO ) 4 ] . (at. no. of Ni = 28 ).

In [ Ni ( CO ) 4 ] , Nickel is in zero valency, i.e., the electronic configuration is [ Ar ] 4 s 2 3 d 8 . The CO is strong field ligand hence two electrons from 4 s transferred to 3 d making it 3 d 10 . The four CO ligands donate electron pairs to the empty 4 s orbital and 4 p orbital giving rise to sp 3 hybrid orbitals. The structure according to literature is tetrahedral which means sp 3 hybridization. All the electrons are paired, so, it is diamagnetic in nature.