Chapter 10 Salts

Question 1

Acid+ metal=

Answer 1

salt+hydrogen

Question 2

Acid+ base/alkali

Answer 2

salt+ water (neutralisation)

Question 3

Acid+ carbonate

Answer 3

salt+ water+ carbon dioxide

Question 4

Nitric acid chemical formula

Answer 4

HNO3

Question 5

Hydrochloric acid chemical formula

Answer 5

HCl

Question 6

Sulfuric acid chemical formula

Answer 6

H2SO4

Question 7

What does solubility mean?

Answer 7

Solubility refers to the maximum amount of substance that can be dissolved in a given volume of solvent (usually water).

Question 8

Which nitrates are soluble?

Answer 8

All nitrates are soluble

Question 9

Which chlorides are insoluble?

Answer 9

Lead(II) chloride, PbCl2
Silver chloride, AgCl

Question 10

Which sulfates are insoluble?

Answer 10

Calcium sulfate, CaSO4
Lead(II) sulfate, PbSO4
Barium Sulfate, BaSO4

Question 11

Which carbonates are soluble?

Answer 11

Sodium carbonate, Na2Co3
Potassium carbonate, K2Co3
Ammonium carbonate, (NH4)2CO3

Question 12

How to prepare non-SPA salts?

Answer 12

-By adding excess metal, metal oxide, metal hydroxide or metal carbonate to acid
-acid+ insoluble = soluble salt

Question 13

How to prepare zinc sulfate?

Answer 13

1. Add excess zinc powder until no more zinc dissolves or no more effervescence (H2) is observed.
2. Filter to remove the excess (unreacted) zinc and obtain zinc sulfate solution as filtrate.
3. Heat the filtrate to obtain a saturated solution. Leave the solution to cool and crytallise.
4. Filter the mixture to obtain zinc sulfate crystals as residue.
5. Rinse the crystal with a little distilled water and dry between sheets of filter paper

Question 14

What is titration use for?

Answer 14

-SPA salts can be prepared by adding an alkali or SPA carbonate to acid
-acid + soluble = soluble salt

Question 15

How to find the exact volume of acid for exact reaction?

Answer 15

1. Pipette 25.0 cm3 of sodium hydroxide into a conical flask
2. Add a few drops of indicator into the flask
3. Add dilute nitric acid slowly from the burette until the solution changes colour permanently
4. Note the volume of acid added

Question 16

Salt preparation for titration steps

Answer 16

1. Repeat the titration without adding the indicator and add the same volume of acid to 25.0cm3 of sodium hydroxide to obtain the salt solution
2. Heat the solution to evaporate the water and obtain a saturated solution
3. Leave the saturated solution to cool so that crystals can form
4. Filter to obtain sodium nitrate crystals as residue
5. Rinse the crystals with a little cold distilled water to remove water-soluble impurities and dry between sheets of filter papers

Question 17

Why cannot add indicator on second titration?

Answer 17

It will make the salt impure.

Question 18

What is precipitation use for?

Answer 18

-Insoluble salts can be prepared by adding two solutions together.
-soluble + soluble = insoluble salt

Question 19

Preparation of Lead(II) sulfate

Answer 19

1. Add excess sodium sulfate to lead(II) nitrate and stir until no more precipitate forms
2. Filter the mixture to obtain lead(II) sulfate as residue
3. Rinse the precipitate with distilled water to remove water-soluble impurities
4. Dry the precipitate between sheets of filter paper

Question 20

Preparation of Lead(II) sulfate

Answer 20

1. Add excess sodium sulfate to lead(II) nitrate and stir until no more precipitate forms
2. Filter the mixture to obtain lead(II) sulfate as residue
3. Rinse the precipitate with distilled water to remove water-soluble impurities
4. Dry the precipitate between sheets of filter paper