Question

Give a balanced equation for each of the following types of reactions:
A direct combination reaction between phosphorus and a neutral gas.
A soluble salt of lead formed from an insoluble base by double decomposition neutralisation.
A thermal decomposition reaction of a salt which results in the formation of nitrogen gas.
A synthesis reaction between a metal & a non-metal resulting in formation of an insoluble salt of iron

Answer 1

1) A direct combination reaction between phosphorus and a neutral gas.

Ans: $\sf \: 4P + 5O_2 \rightarrow 2P_2O_5$

2)A soluble salt of lead formed from an insoluble base by double decomposition - neutralisation.

Ans: $\sf{PbO + 2HNO_3 \rightarrow Pb(NO_3)_2+H_2O}$

3) A thermal decomposition reaction of a salt which results in the formation of nitrogen gas

Ans:$\sf{(NH_4)_2Cr_2O_7 \rightarrow Cr_2O_3 +4H_2O +N_2}$

4) A synthesis reaction between a metal & a non-metal resulting in formation of an insoluble salt of iron

Ans: $\sf Fe+ S \rightarrow FeS$

Answer 2

Answer:

• A direct combination reaction between phosphorus (P) and a neutral gas (O₂) will give phosphorous pentoxide.

                     $4P+5O_{2}$   →   $P_{2}O_{5}$

• Formation of a soluble salt of lead (Pb) by double decomposition neutralization from an insoluble base:

                    $PbO +2HNO_{3}$  →  $Pb(NO_{3})_{2} +H_{2}O$

        Here, Pb(NO₃)₂ is the soluble salt of lead.

• A thermal decomposition reaction of a salt (NH₄)₂Cr₂O₇ which results in the formation of nitrogen gas.

            $(NH_{4})_{2}Cr_{2}O_{7}$  →  $Cr_{2}O_{3}+4H_{2}O+N_{2}$

• A synthesis reaction between a metal iron (Fe) & a non-metal Sulphur (S) resulting in formation of an insoluble salt of iron which FeS.

                       $Fe$    +   $S$   →   $FeS$