ch8

Question 1

Which salts are soluble?

Answer 1

grp1 + ammonium salts

Question 2

What is a salt?

Answer 2

any compound, 1 cation, 1 anion

hydrogen in acid, replaced by metal/NH4+

Question 3

Which carbonates are soluble?

Answer 3

grp1 + ammonium carbonates

yes, ammonium carbonate exists.

Question 4

3 ways to prepare salt

Answer 4

• precipitation
• excess solid reactant method
• titration

Question 5

Which way to prepare insoluble salt?

Answer 5

precipitation only

Question 6

when wan prepare soluble salt.

Answer 6

• add excess solid reactant (non-SPA)
• titration (SPA)

nitrates use excess solid reactant!!!!!!!!!

add excess solid reactant aka filtration and crystalisation

Question 7

precipitation eqn

Answer 7

soluble acid/alkali/salt + soluble salt = insoluble salt + soluble salt

precipitation only for insoluble salt formation

all salts dissociate to give 1 cation 1 anion. The grp it belongs to dosen’t matter! Only the solubility.

Question 8

Steps of precipitation

Answer 8

1. Add 1 soluble salt + 1 soluble substance, wait till reaction finishes
2. Pour mixture thru filter paper, retrieve residue, wash w/ distilled water, press dry residue

Question 9

when will precipitation not happen? (despite mixing 2 salts)

Answer 9

1. When both salt in end products are soluble

Precipitation MUST produce 1 insoluble salt + 1 soluble salt

2. When both salts have same anion
   e.g. BaCl + HCl = no reaction

Question 10

is precipitation a chemical reaction? Will mixing 1 sol. salt and 1 sol. substance always cause a chemical reaction to happen?

Answer 10

yes, ppt. -> chem reaction
when 1 soluble salt + 1 soluble substance mix, no insoluble salt = no reaction. They mix

Question 11

are all chlorides soluble in water? which chloride is insoluble in water?

Answer 11

No. All chlorides are soluble except these:
Long Story
Lead Silver

Question 12

Souble SPA/Group 1 salts how to prepare

Answer 12

Titration

Question 13

Soluble Non-SPA/Non-Group 1 salts how to prepare?

Answer 13

excess solid reactant method

**nitrate is under Excess Solid Reactant Method!

SPAN - Solubility
SPA - Group 1 + Ammonium

Question 14

how to prepare insoluble salt lead sulfate (reactants only)

Answer 14

sodium_____ + _____ nitrate

sodium sulfate + lead nitrate

Question 15

How to do excess solid reactant method (eq)?

Answer 15

acid + metal
acid + insoluble base
acid + insoluble carbonate

Question 16

How to do titration method? (eq)

Answer 16

acid + soluble alkali/soluble carbonate

all acids are soluble.

Question 17

Are all sulfate salts soluble?

Answer 17

generally yes

exceptions
Calcium
Lead(II)
Barium

Chinese
Language
Bad

Calcium
Lead(iI)
Barium

Question 18

Are all chlorides/iodides soluble?

Answer 18

generally yes

exceptions
- lead(II)
- silver

Question 19

are hydroxide and oxide soluble? are they bases?

Answer 19

all hydroxide/oxide insoluble except (SPA + grp1)

LINK
All hydroxide, oxides bases
- however, except SPA+Grp1 + calcium, all hydroxide, oxide are insoluble bases.

Question 20

is potassium metal suitable to use in a school lab to react with acid?

Answer 20

No.
Potassium reacts violently with acid (highest in reactivity series)

Question 21

can solid calcium nitrate and solid potassium sulfate react?

Answer 21

no.

solid + aqueous can react, but solid + solid cant!!

for ppt, both must be soluble!

solid + (aq) can react!

Question 22

why aqueous sodium hydroxide and hydrochloric acid suitable for titration?

Answer 22

• dissolve in water, can react
• aq soln. can place into burette/pipette

Question 23

how to obtain pure dry sample of titrated solution?

Answer 23

crystallisation, always (except for sodium chloride)

Question 24

why must excess reactant be added at excess reactant method?

Answer 24

ensure all acid completely reacted -> prevent contamination

solid reactant wont all dissolve… its called excess for a reason, bruh!

Question 25

steps for excess solid reactant method

Answer 25

1. mix acid with **excess solid** reactant, **stir thoroughly** 2. filter mixture 3. heat filtrate in **evaporating dish**, point of saturation 4. allow time for liquid to cool, **crystalisation**, form crystals 5. wash crystals with **distilled water**, press dry between few sheets of filter paper ## Footnote no methyl orange! Methyl orange will **contaminate soln.**

Question 26

When I do excess calcium carbonate + sulfuric acid yield is very low. Why?

Answer 26

**product: calcium sulfate** - calcium sulfate formed insoluble - forms layer around calcium carbonate - prevents calcium carbonate from **further** reacting ## Footnote **LINK** Chinese Language Basic Calcium sulfate is one insoluble salt

Question 27

does hydroxide constitute of sulfur hydroxide?

Answer 27

**no** (all metal except gold) hydroxide only exists ## Footnote includes copper hydroxide

Question 28

epsom salt chem formula

Answer 28

MgSo4

Question 29

what is filtration (excess solid reactant) for?

Answer 29

ensure excess residue trapped -> filter paper, no contamination, crystals

Question 30

why heat acid (excess solid reactant)

Answer 30

speed up rate of reaction

Question 31

hydrogen ion vs hydride

Answer 31

hydrogen ion: H+ hydride: H-

Question 32

usage of salt

Answer 32

sodium flouride in toothpaste

Question 33

why must have 1 insoluble in water reactant in excess solid reactant

Answer 33

excess starting materials can be removed from salt soln via filtration

Question 34

better acid + metal carbonate than acid + metal, excess solid reactant

Answer 34

1. some very reactive metals, violent reaction, dangerous 2. unreactive metals dun react w/ dilute acid

Question 35

titration why must volume of reactants be exact

Answer 35

both reactants (aq) excess reactant, cannot be filtered impure salt

Question 36

sodium salts usage

Answer 36

sodium chloride preservation