ch8 Flashcards
Which salts are soluble?
grp1 + ammonium salts
What is a salt?
any compound, 1 cation, 1 anion
hydrogen in acid, replaced by metal/NH4+
Which carbonates are soluble?
grp1 + ammonium carbonates
yes, ammonium carbonate exists.
3 ways to prepare salt
- precipitation
- excess solid reactant method
- titration
Which way to prepare insoluble salt?
precipitation only
when uw react 2 salts and at least 1 of them are soluble…
methods
- add excess solid reactant (non-SPA)
- titration (SPA)
nitrates use excess solid reactant!!!!!!!!!
add excess solid reactant aka filtration and crystalisation
precipitation eqn
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.
Steps of precipitation
- Add 1 soluble salt + 1 soluble substance, wait till reaction finishes
- Pour mixture thru filter paper, retrieve residue, wash w/ distilled water, press dry residue
barium nitrate + sodium carbonate -> ?
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
when will precipitation not happen? (despite mixing 2 salts)
- When both salt in end products are soluble
Precipitation MUST produce 1 insoluble salt + 1 soluble salt
- When both salts have same anion
e.g. BaCl + HCl = no reaction
is precipitation a chemical reaction? Will mixing 1 sol. salt and 1 sol. substance always cause a chemical reaction to happen?
yes, ppt. -> chem reaction
when 1 soluble salt + 1 soluble substance mix, no insoluble salt = no reaction. They mix
are all chlorides soluble in water? which chloride is insoluble in water?
No. All chlorides are soluble except these:
Long Story
Lead Silver
Souble SPA/Group 1 salts how to prepare
Titration
Soluble Non-SPA/Non-Group 1 salts how to prepare?
excess solid reactant method
**nitrate is under Excess Solid Reactant Method!
SPAN - Solubility
SPA - Group 1 + Ammonium
how to prepare insoluble salt lead sulfate (reactants only)
sodium_____ + _____ nitrate
sodium sulfate + lead nitrate
How to do excess solid reactant method (eq)?
acid + metal
acid + insoluble base
acid + insoluble carbonate
How to do titration method? (eq)
acid + soluble alkali/soluble carbonate
all acids are soluble.
Are all sulfate salts soluble?
generally yes
exceptions
Calcium
Lead(II)
Barium
Chinese
Language
Bad
Calcium
Lead(iI)
Barium
Are all chlorides/iodides soluble?
generally yes
exceptions
- lead(II)
- silver
are hydroxide and oxide soluble? are they bases?
all hydroxide/oxide insoluble except (SPA + grp1)
LINK
All hydroxide, oxides bases
- however, except SPA+Grp1 + calcium, all hydroxide, oxide are insoluble bases.
is potassium metal suitable to use in a school lab to react with acid?
No.
Potassium reacts violently with acid (highest in reactivity series)
can solid calcium nitrate and solid potassium sulfate react?
no.
solid + aqueous can react, but solid + solid cant!!
for ppt, both must be soluble!
solid + (aq) can react!
when to write “Aqueous”?
when uw indicate it is soluble substance/salt
why aqueous sodium hydroxide and hydrochloric acid suitable for titration?
- soluble in water
- aq soln. can place into burette/pipette
how to obtain pure dry sample of titrated solution?
crystallisation, always (except for sodium chloride)
why must excess reactant be added at excess reactant method?
ensure all acid completely reacted -> prevent contamination
solid reactant wont all dissolve… its called excess for a reason, bruh!
steps for excess solid reactant method
- mix acid with excess solid reactant, stir thoroughly
- filter mixture
- heat filtrate in evaporating dish, point of saturation
- allow time for liquid to cool, form crystals
- wash crystals with distilled water, press dry between few sheets of filter paper
no methyl orange! Methyl orange will contaminate soln.
When I do excess calcium carbonate + dilute sulfuric acid yield is very low. Why?
product: calcium sulfate
- calcium sulfate formed insoluble
- forms layer around calcium carbonate
- prevents calcium carbonate from further reacting
LINK
Chinese
Language
Basic
Calcium sulfate is one insoluble salt
does hydroxide constitute of sulfur hydroxide?
no
(all metal except gold) hydroxide only exists
includes copper hydroxide
epsom salt chem formula
MgSo4
for alkali, can it be ___ oxide?
no!
can be ___ hydroxide, aq ammonia but CANNOT BE OXIDE!
what is filtration (excess solid reactant) for?
ensure excess residue trapped -> filter paper, no contamination, crystals
why heat acid (excess solid reactant)
speed up rate of reaction
hydrogen ion vs hydride
hydrogen ion: H+
hydride: H-
