Acids & Bases + Tests Flashcards
How many protons does a hydrogen ion have
1 proton
An acid is a ____ donor?
Acid –> proton donor
What must an acid have to donate a hydrogen ion (proton)
An acid must have a hydrogen to donate a hydrogen ion (proton)
What do acids dissociate into when ____ is added?
They dissociate (split up) into hydrogen ions and negative ions (anions) when added to water
A base is a _____ _______?
Base –> proton acceptor
Bases must be able to accept a what ion?
Bases must accept a hydrogen ion (proton)
What is an alkali?
A soluble base
What do bases dissociate into when _____ is added?
When WATER is added, bases dissociate into hydroxide ions and positive metal ions (cations)
Neutralisation reactions are when…
Net ionic equation for all acid-base neutralisation reactions?
Leads to a _____ solution?
⭐ when acids react with alkali
⭐ H+ + OH- -> H2O
⭐ leads to a NEUTRAL solution
Strong Vs. Weak Acid
What does strong acid dissociate into?
Example?
Strong acid FULLY dissociates into water and H+ (hydrogen) ions, all hydrogen ions are donated and separate from the anions.
HCl (aq) -> H+ (aq) + Cl- (aq)
What does weak acid dissociate into?
Example?
What does ⇌ mean?
Weak acid: partially dissociates in water into H+ (hydrogen) ions, some H+ (hydrogen ions) are donated and the system forms equilibrium
CH3COOH (aq) ⇌ H+ (aq) + CH3COO- (aq)
⇌ = reversible, “can go back and forth”; a reversible reaction in which both the reactants and products are forming at the same time.
Does a weak or strong acid have more H+ ions?
Strong acids have more H+ ions in solution that weak acids.
Are metal oxides acidic or basic?
BASIC
amphoteric
dissolve in H2O
Are non-metal oxides acidic or basic?
ACIDIC
will react with an acid and be neutralised
What does amphoteric mean?
Examples?
Can react like an acid OR base
Al(OH)3
Al2O3
ZnO
What does amphiprotic mean?
Examples?
Donate AND accept hydrogen ions (H+)
H2O + H+ –> H3O+ [hydronium ion; accepting a hydrogen ion, showing water reacting like a base]
Cl- + H2O –> OH- + HCl [donates H+ to the Cl and makes HCl; acting as an acid]
acid + hydroxide/oxide =>
salt + water
acid + metal carbonate =>
salt + water + carbon dioxide
acid + metal =>
salt + hydrogen
Reaction for limewater
Ca(OH)2 + CO2 => CaCO3 + H2O
limewater + carbon dioxide => limestone [cloudy, milky] + water
Limestone Cycle
=> Limestone (CaCO3)
CO2. Burning or slaking. Heat 1100 degrees Celcius.
=> Quick lime CaO + CO2
Heat. Hydration or slaking.
Add water
=> Ca(OH)2 + H2O -> CaO [above] + CO2
=> Slaked lime. Ca(OH)2
+ H2O
=> back to
MS FORM
Limewater goes…
Chemical formula of limewater?
Limestone rock?
Limewater goes cloudy
Calcium hydroxide
Sedimentary rock
common uses of limestone (CaCO3)
building materials
manufacture of cement
common uses of CaO
wastewater treatment
neutralisation of acidic soil
What is produced when calcium carbonate undergoes thermal decomposition?
Calcium oxide
chemical name for slaked lime?
calcium hydroxide
What is formed when excess carbon dioxide is bubbled through limewater?
calcium hydrogen carbonate
Why does limewater appear milky when carbon dioxide is bubbled through it?
calcium carbonate is insoluble in water
What is the correct balanced symbol equation for the formation of solid slaked lime?
a) CaO(s) + H2O(l) → 2CaOH2(s)
b) CaO(s) + H2O(l) → Ca(OH)2(aq)
c) CaO(s) + H2O(l) → Ca(OH)2(s
c)
What is the correct balanced symbol equation for the formation of solid quick lime (CaO)?
a) CaCO3(s) → CaO(s) + H2O(l)
b) CaCO3(s) → CaO(s) + CO2(g)
c) CaO(s) + H2O(l) → Ca(OH)2(s)
b)
FORMATION so on the right
What is the correct balanced symbol equation for the formation of solid limestone?
a) CaCO3(s) → CaO(s) + H2O(l)
b) Ca(OH)2 (aq) + CO2 (g) → CaCO3 (s)
c) CaCO3 (s) → CaO (s) + CO2 (g)
b)
formation so right side
Flame tests of metal ions
- Lithium Li+
Red
Sodium Na+
Yellow
Potassium K+
Lilac
Copper (II) (Cu2+)
Blue
Calcium Ca2+
Orange
Barium Ba2+
Light green
Testing for anions - anion, test, test result
- Carbonate CO3 2-
Add dilute acid
Bubbles (CO2/milky)
- Chloride Cl- in solution
Acidify with dilute nitric acid,
+ add aqueous silver nitrate
White ppt (AgCl)
- Bromide Br- in solution
Acidify with dilute nitric acid,
+ add aqueous silver nitrate
Cream ppt (AgBr)
Iodide I- in solution
Acidify with dilute nitric acid,
+ add aqueous silver nitrate
Yellow ppt (AgI)
Nitrate NO3- in solution
Add aqueous sodium hydroxide, then aluminium foil; warm carefully
NH3
turns blue
Sulfate SO4 2- in solution
Acidify, then add aqueous barium nitrate
White ppt (BaSO4)
Sulfite SO3 2-
Add dilute hydrochloric acid, warm gently and test for the presence of sulfur dioxide
SO2
Decolourises
Testing for aqueous cations - cation,
test effect of AQUEOUS SODIUM HYDROXIDE,
effect of aqueous ammonia
- Aluminium Al3+
White ppt
Soluble
- Ammonium NH4+
No ppt
Produces NH3 on heating
- Calcium Ca2+
White ppt
Insoluble
- Chromium (III) Cr3+
Green ppt
Soluble
- Copper (II) Cu2+
Light blue ppt
Insoluble
- Iron (II) Fe2+
Green ppt
Insoluble
- Iron (III) Fe3+
Red-brown ppt
Insoluble
Zinc Zn2+
White ppt
Soluble
Tests for gases - test, observation
- Ammonia NH3
Test: damp red litmus
Observation: litmus paper turn blue/purple
- Carbon dioxide CO2
Test: bubble the gas through limewater
Observation: limewater goes milky/cloudy
Chlorine Cl2
Test: damp blue litmus
Observation: litmus turns red or white/bleached
Hydrogen H2
Test: splint
Observation: squeaky pop/flame flickered
Oxygen O2
Test: glowing splint
Observation: lots of smoke, splint relit
Sulfur dioxide SO2
Test: potassium permanganate paper
Observation: purple to colourless
