Question

Attempt either option (A) or (B):

(A) Write chemical equations for the following when: (a) Silver bromide is exposed to sunlight. (b) A piece of lead metal is dropped into copper (II) chloride solution. (c) Hydrogen gas is passed over heated copper oxide. (d) Methane gas is burnt in air. (e) Quick lime is mixed with water.

OR

(B) (a) Study the experimental setup shown in the diagram (heating lead nitrate in a boiling tube) and write chemical equation for the same. Name and define the type of reaction. Mention the colour of the products formed. (b) What type of reaction takes place when aqueous solution of lead (II) nitrate and potassium iodide are mixed together? Write chemical equation also.

Accepted Answer

(A) (a) 2AgBr -> 2Ag + Br2, (b) Pb + CuCl2 -> PbCl2 + Cu, (c) CuO + H2 -> Cu + H2O, (d) CH4 + 2O2 -> CO2 + 2H2O, (e) CaO + H2O -> Ca(OH)2. (B) Thermal decomposition of Pb(NO3)2; Double displacement/Precipitation forming yellow PbI2.. **Option (A):** (a) $2AgBr(s) \xrightarrow{	ext{Sunlight}} 2Ag(s) + Br_2(g)$ (b) $Pb(s) + CuCl_2(aq) ightarrow PbCl_2(aq) + Cu(s)$ (c) $CuO(s) + H_2(g) \xrightarrow{\Delta} Cu(s) + H_2O(g)$ (d) $CH_4(g) + 2O_2(g) ightarrow CO_2(g) + 2H_2O(g) + 	ext{Heat}$ (e) $CaO(s) + H_2O(l) ightarrow Ca(OH)_2(aq) + 	ext{Heat}$ **Option (B):** (a) $2Pb(NO_3)_2(s) \xrightarrow{\Delta} 2PbO(s) + 4NO_2(g) + O_2(g)$ - Type: Thermal Decomposition (breakdown by heat). - Colours: $PbO$ is yellow residue, $NO_2$ is brown fumes. (b) Double Displacement / Precipitation reaction: $Pb(NO_3)_2(aq) + 2KI(aq) ightarrow PbI_2(s)\downarrow + 2KNO_3(aq)$ Yellow precipitate of $PbI_2$ is formed.

Types of Chemical Reactions and Equations

Explanation

Practise this under board exam conditions