Calcium reacts with cold water to form calcium hydroxide, $\mathrm{Ca}{\left(\mathrm{OH}\right)}_2$, and hydrogen, ${\mathrm{H}}_2$. Write two half-equations, for the reaction between water and calcium  to show:

The change from calcium to calcium ions.

 

Calcium reacts with cold water to form calcium hydroxide, $\mathrm{Ca}{\left(\mathrm{OH}\right)}_2$, and hydrogen, ${\mathrm{H}}_2$. Write two half-equations, for the reaction between water and calcium to show:

The change from water to hydroxide ions and hydrogen.

Calcium reacts with cold water to form calcium hydroxide, $\mathrm{Ca}{\left(\mathrm{OH}\right)}_2$, and hydrogen, ${\mathrm{H}}_2$. Explain the role played by water in this reaction.

The unbalanced equation for the reaction of sulphur dioxide with bromine is as shown below:

${\mathrm{SO}}_2+{\mathrm{Br}}_2+{\mathrm{H}}_2\mathrm{O}\stackrel{ }{\to }{{\mathrm{SO}}_4}^{2-}+{\mathrm{Br}}^{-}+{\mathrm{H}}^{+}$

State the oxidation number of sulphur in ${\mathrm{SO}}_2$.

The unbalanced equation for the reaction of sulphur dioxide with bromine is as shown below:

${\mathrm{SO}}_2+{\mathrm{Br}}_2+{\mathrm{H}}_2\mathrm{O}\stackrel{ }{\to }{{\mathrm{SO}}_4}^{2-}+{\mathrm{Br}}^{-}+{\mathrm{H}}^{+}$

State the oxidation number of sulphur in ${{\mathrm{SO}}_4}^{2-}$.

The unbalanced equation for the reaction of sulphur dioxide with bromine is as shown below:

${\mathrm{SO}}_2+{\mathrm{Br}}_2+{\mathrm{H}}_2\mathrm{O}\stackrel{ }{\to }{{\mathrm{SO}}_4}^{2-}+{\mathrm{Br}}^{-}+{\mathrm{H}}^{+}$

State the oxidation number of bromine in ${\mathrm{Br}}_2$.

The unbalanced equation for the reaction of sulphur dioxide with bromine is as shown below:

${\mathrm{SO}}_2+{\mathrm{Br}}_2+{\mathrm{H}}_2\mathrm{O}\stackrel{ }{\to }{{\mathrm{SO}}_4}^{2-}+{\mathrm{Br}}^{-}+{\mathrm{H}}^{+}$

State the oxidation number of bromine in ${\mathrm{Br}}^{-}$.