salts

Question 1

group 1 and ammonium salts

Answer 1

all soluble

Question 2

nitrates

Answer 2

all nitrates are soluble

Question 3

all sulfates are…

Answer 3

soluble except for lead sulfate and barium sulfate

Question 4

all chlorides/iodides/bromides are soluble except..

Answer 4

silver and lead (||) chlorides/iodide/bromide

Question 5

all carbonates are…

Answer 5

insoluble except for group 1 and ammonium carbonates

Question 6

all metal oxides are…

Answer 6

insoluble except for group 1 oxides

Question 7

all metal hydroxides are…

Answer 7

insoluble except for group 1 hydroxides

Question 8

how do you prepare an insoluble salt?

Answer 8

precipitation (both are soluble starting materials)

Question 9

how do you prepare a soluble salt?

Answer 9

reaction with acids

Question 10

what are the two methods of reaction with acids (include the type of starting materials)

Answer 10

titration
- soluble starting materials
- acid and soluble carbonate
OR acid & alkali

reaction of acid with an insoluble substance
- acid & excess insoluble base/carbonate OR acid & excess metal

Question 11

what is precipitation?

Answer 11

It is a reaction involving mixing two aqueous solutions to form an insoluble solid that
separates out from the reaction mixture. The insoluble solid is the precipitate.

Question 12

what is the procedure of precipitation?

Answer 12

1. 2 solutions are selected. One of the reagents contributes the cation, Xn+, while another contributes the anion Ym-
   . For example, to prepare an insoluble salt, PbSO4, we can mix two aqueous
   solutions:  lead(II) nitrate (for the Pb2+ cation)  sodium sulfate (for the SO4
2. Mix the 2 solutions together. One of the reagents will be added in excess and
   would be left as the unreacted reagent.
   When lead(II) nitrate and sodium sulfate are mixed, an insoluble salt, PbSO4, and
   an aqueous solution, NaNO3, are formed.

Pb(NO3)2 (aq) + Na2SO4 (aq)  PbSO4 (s) + 2NaNO3 (aq)

3. The insoluble salt is formed as a precipitate and can then be separated from the
   aqueous solution by filtration.
4. The salt is then washed with distilled water and wiped dry with filter paper to
   remove contaminant chemicals that are on the surface of the crystals.

Question 13

what are the steps taken for solid-acid reaction?

Answer 13

1. Add excess insoluble carbonate/base/metals into dilute acid in a beaker.
   (For example, to prepare a soluble salt, CuSO4, we can add excess copper(II) oxide, an
   insoluble reactant, to sulfuric acid.)
   Warm the reactants. The solid react with acid to form salt and water. Since the solid
   is added in excess, all the acid will be used up and the excess solid remain as
   insoluble solid.
2. The resultant mixture can then be filtered to remove the excess, unreacted solids.
   The filtrate is the solution of the soluble salt.
3. Heat the filtrate gently until it is saturated.
4. Allow the saturated solution to cool for the crystals to form.
5. Filter the mixture to collect the crystals.
6. Wash the soluble salt crystals with a small amount of cold distilled water. Dry the crystals between pieces of filter paper.

Question 14

what is the procedure for titration?

Answer 14

1. Fill up a burette with 0.1 mol/dm3

of dilute nitric acid.

2. Pipette 25.0 cm3

of 0.1 mol/dm3

of aqueous sodium hydroxide into a conical flask.
3. Add a few drops of phenolphthalein indicator (or any other suitable indicator) to
the solution in the conical flask.
4. Titrate the sodium hydroxide solution with the dilute nitric acid until the solution
changes from pink to colourless permanently in a single drop (or the corresponding
colour change based on the indicator used).
5. Note the volume of dilute nitric acid added.
6. Repeat the experiment without the indicator.
7. Add the same volume of acid (from step 5) from the burette. This gives a solution
of the salt, without excess acid or alkali.
8. Heat the solution till saturated.
9. Allow the solution to cool for the crystals to form.
10. Filter the mixture to remove excess solution/water.
11. Wash the crystals with a small amount of cold distilled water.
12. Dry the crystals by pressing between sheets of filter paper.