Determine if the reaction produces a precipitate. For a
precipitate mark ‘a’ and if there is no precipitate mark ‘b’.
8. KOH(aq) + Fe(NO3)3(aq)
9. MgCl2(aq) + Na(NO3)2(aq)
10. NaBr(aq) + Ag(NO3) (aq)
11. Na3PO4(aq) + Ba(NO3) 2(aq)
8. Fe(OH)3 will ppt.
9. no reaction.
10. AgBr will ppt.
11. Ba3(PO4)2 will ppt.
To determine if a reaction produces a precipitate, you need to know the solubility rules for the different ions involved in the reaction. These solubility rules provide guidelines on which compounds are soluble (dissolve in water) and which are insoluble (form a precipitate) in water.
Let's analyze each reaction and determine if a precipitate is formed:
8. KOH(aq) + Fe(NO3)3(aq) →
According to the solubility rules, hydroxides (OH-) are usually insoluble, except for Group 1A (Li+, Na+, K+, etc.) and ammonium (NH4+) compounds. Iron(III) nitrate (Fe(NO3)3) is a soluble salt. Therefore, when potassium hydroxide (KOH) is added to iron(III) nitrate, a precipitate is formed.
Result: Precipitate forms. Mark 'a'.
9. MgCl2(aq) + Na(NO3)2(aq) →
Both magnesium chloride (MgCl2) and sodium nitrate (Na(NO3)2) are soluble compounds according to the solubility rules. Therefore, when they are combined, no precipitate is formed.
Result: No precipitate forms. Mark 'b'.
10. NaBr(aq) + Ag(NO3)(aq) →
According to the solubility rules, silver halides (AgX) are insoluble except for silver chloride (AgCl), silver bromide (AgBr), and silver iodide (AgI). Sodium bromide (NaBr) and silver nitrate (Ag(NO3)) are soluble. Therefore, when they are combined, a precipitate of silver bromide (AgBr) is formed.
Result: Precipitate forms. Mark 'a'.
11. Na3PO4(aq) + Ba(NO3)2(aq) →
According to the solubility rules, most phosphates (PO4^3-) are insoluble, except for those of Group 1A and ammonium (NH4+). Barium nitrate (Ba(NO3)2) is soluble. Therefore, when sodium phosphate (Na3PO4) is added to barium nitrate, a precipitate of barium phosphate (Ba3(PO4)2) is formed.
Result: Precipitate forms. Mark 'a'.
In summary:
8. KOH(aq) + Fe(NO3)3(aq) → Precipitate forms. Mark 'a'.
9. MgCl2(aq) + Na(NO3)2(aq) → No precipitate forms. Mark 'b'.
10. NaBr(aq) + Ag(NO3)(aq) → Precipitate forms. Mark 'a'.
11. Na3PO4(aq) + Ba(NO3)2(aq) → Precipitate forms. Mark 'a'.