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 uw react 2 salts and at least 1 of products are soluble…
methods

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

barium nitrate + sodium carbonate -> ?

Answer 9

remember all salts have 1 cation 1 anion

Step 1: precipitation eqn
soluble salt + soluble substance
e.g. Barium chloride + Sodium Hydroxide

Step 2: AB + CD = AD + BC
Barium chloride + sodium hydroxide -> barium hydroxide + sodium chloride

Step 3: See if there is 1 insol. salt. in products. Ppt. reaction must have
Products: Barium hydroxide + sodium chloride

Barium hydroxide insoluble (all hydroxide insoluble except grp1)

criteria met = got reaction

Step 4: Write No Reaction if there is no insol. salt

hydroxide, oxide, carbonate, salts soluble: grp1+ammonium

sulfate soluble: all except Chinese Language Basic (Calcium Lead(II) Barium)

chloride, iodide soluble: all except silver, Lead(II)

nitrate soluble: all

Question 10

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

Answer 10

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 11

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

Answer 11

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

Question 12

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

Answer 12

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

Question 13

Souble SPA/Group 1 salts how to prepare

Answer 13

Titration

Question 14

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

Answer 14

excess solid reactant method

**nitrate is under Excess Solid Reactant Method!

SPAN - Solubility
SPA - Group 1 + Ammonium

Question 15

how to prepare insoluble salt lead sulfate (reactants only)

Answer 15

sodium_____ + _____ nitrate

sodium sulfate + lead nitrate

Question 16

How to do excess solid reactant method (eq)?

Answer 16

acid + metal
acid + insoluble base
acid + insoluble carbonate

Question 17

How to do titration method? (eq)

Answer 17

acid + soluble alkali/soluble carbonate

all acids are soluble.

Question 18

Are all sulfate salts soluble?

Answer 18

generally yes

exceptions
Calcium
Lead(II)
Barium

Chinese
Language
Bad

Calcium
Lead(iI)
Barium

Question 19

Are all chlorides/iodides soluble?

Answer 19

generally yes

exceptions
- lead(II)
- silver

Question 20

are hydroxide and oxide soluble? are they bases?

Answer 20

all hydroxide/oxide insoluble except (SPA + grp1)

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

Question 21

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

Answer 21

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

Question 22

can solid calcium nitrate and solid potassium sulfate react?

Answer 22

no.

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

for ppt, both must be soluble!

solid + (aq) can react!

Question 23

when to write “Aqueous”?

Answer 23

when uw indicate it is soluble substance/salt

Question 24

why aqueous sodium hydroxide and hydrochloric acid suitable for titration?

Answer 24

• soluble in water
• aq soln. can place into burette/pipette

Question 25

how to obtain pure dry sample of titrated solution?

Answer 25

crystallisation, **always** (except for sodium chloride)

Question 26

why must excess reactant be added at excess reactant method?

Answer 26

ensure all **acid** completely reacted -> prevent contamination ## Footnote solid reactant wont all dissolve... its called **excess** for a reason, bruh!

Question 27

steps for excess solid reactant method

Answer 27

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 28

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

Answer 28

**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 29

does hydroxide constitute of sulfur hydroxide?

Answer 29

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

Question 30

epsom salt chem formula

Answer 30

MgSo4

Question 31

for alkali, can it be ___ oxide?

Answer 31

**no!** can be ___ hydroxide, aq ammonia but CANNOT BE OXIDE!

Question 32

what is filtration (excess solid reactant) for?

Answer 32

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

Question 33

why heat acid (excess solid reactant)

Answer 33

speed up rate of reaction

Question 34

hydrogen ion vs hydride

Answer 34

hydrogen ion: H+ hydride: H-