Question

Which net ionic equation would match this description of a chemical reaction: When a

solution of magnesium nitrate is mixed with a solution of sodium phosphate, the solid that forms is magnesium phosphate.

a. Mg(NO3)2(aq) + Na2PO4(aq) à MgPO4(s) + NaNO3(aq)

b. Mg2+(aq) + PO43-(aq) à MgPO4(s)

c. 3Mg(NO3)2(aq) + 2Na3PO4(aq) à Mg3(PO4)2(s) + 6NaNO3(aq)

d. 3Mg2+(aq) + 2PO43- à Mg3(PO4)2(s)

e. 3Mg2+(aq) + 6NO3-(aq) + 6Na+(aq) + 2PO43- àMg3(PO4)2(s) + 6NO3-(aq) + 6Na+(aq)

It shuld be D correct?

Answer 1

`3Mg^(2+)(aq.)+2PO_(4)^(3-)(aq.)\rightarrow Mg_(3)(PO_(4))_(2)(s)`

Step-by-step explanation:

`Mg(NO_(3))_(2)`,
`Na_(3)PO_(4)` are strong electrolytes. Hence they are fully ionized in aqueous solution.

`Mg_(3)(PO_(4))_(2)` is a sparingly soluble salt. Hence it remains undissociated in aqueous solution.

So, total ionic equation:

`3Mg^(2+)(aq.)+6NO_(3)^(-)(aq.)+6Na^(+)(aq.)+2PO_(4)^(3-)(aq.)\rightarrow Mg_(3)(PO_(4))_(2)(s)+6Na^(+)(aq.)+6NO_(3)^(-)(aq.)`

Net ionic equation is written by omitting spectator ions from total ionic equation.

Here,
`Na^(+)` and
`NO_(3)^(-)` ions are spectator ions as they remain present on both side of total ionic equation.

So, net ionic equation:

`3Mg^(2+)(aq.)+2PO_(4)^(3-)(aq.)\rightarrow Mg_(3)(PO_(4))_(2)(s)`

So, option (d) is correct.