What is the difference between displacement and double displacement reactions ? Write equations for these reactions.
In a displacement reaction, a more reactive element replaces a less reactive element from a compound.
$A + BX \longrightarrow AX + B$; where $A$ is more reactive than $B$
In a double displacement reaction, two atoms or a group of atoms switch places to form new compounds.
$AB + CD \longrightarrow AD + CB$
For example :
Displacement reaction :
$CuS{O_{4(aq)}}\, + \,Z{n_{(s)}}\, \to \,ZnS{O_{4(aq)}}\, + \,C{u_{(s)}}\,$
Double displacement reaction :
$N{a_2}S{O_{4(aq)}}\, + \,BaC{l_2}_{(aq)}\, \to \,BaS{O_{4(s)}}\, + \,2NaC{l_{(aq)}}\,$
Write one equation each for decomposition reactions where energy is supplied in the form of heat, light or electricity.
A solution of a substance $‘X’$ is used for whitewashing.
$(i)$ Name the substance $‘X’$ and write its formula.
$(ii)$ Write the reaction of the substance $‘X’$ named in $(i)$ above with water.
Write the balanced equation for the following chemical reactions.
$(i)$ Hydrogen $+$ Chlorine $\to $ Hydrogen chloride
$(ii)$ Barium chloride $+$ Aluminium sulphate $\to $ Barium sulphate $+$ Aluminium chloride
$(iii)$ Sodium $+$ Water $\to $ Sodium hydroxide $+$ Hydrogen
Why are decomposition reactions called the opposite of combination reactions? Write equations for these reactions.
Why is respiration considered an exothermic reaction ? Explain.