ch7 acid base Flashcards
Fill in the blanks.
More acid means more ___ ions.
More alkaline means more ___ ions
More acid means H+ ions
More alkali means OH- ions
Rate of acid ionising meaning + represents?
- ability for acid to release hydrogen ion (acidity)
- more H+ ions released = more acidic, strong // weak
EXAMPLE BETWEEN 1 STRONG ACID, 1 WEAK ACID
Ionisation of 10,000 HCl molecules -> 10,000 H+ atoms + 10,000 Cl - atoms
Ionisation of 10,000 CH3COOH -> 3 Ch3Cooh- molecules + 3 H+ atoms
**Therefore, strong acid HCl is so much more strong (10,000 H+ atoms) as compared to weak acid
EXAMPLE BETWEEN 2 STRONG ACIDS
Ionisation of HCl -> H+ Cl
Ionisation of nitric acid -> 2H+ + No3-
CH3COOH (3 H+ atoms)
name of salt produced if reacted with…
- sulfuric acid
- nitric acid
- hydrochloric acid
- phosphoric acid
- ethanoic acid
- sulfate
- nitrate
- chloride
- phosphate
- ethanoate
4 eqn.
(acid + ___)
alkali + ammonium salt -> ammonia + salt + water
acid + alkali/base -> salt + water
acid + reactive metal -> salt + hydrogen
acid + carbonate -> salt + carbon dioxide + water
ammonium only found in salts
ALKALIIIIIII!!!!!!
3 unreactive metals
- gold
- silver
- copper
just happens to correspond to 3 tiers of medals
however, silver, copper oxide exists while gold oxide dosent
which keywords signalises a base/akali?
- (all metal except gold) oxide
- (all metal except gold) hydroxide
definition of base is still:
oxide formed w/ reactive metal, reacts w/ acid to form salt, water
what is —> in chemical eqn? What does it show?
- strong acid/alkali
- complete ionisation
- irreversible reaction
what is
⇌
in chemical eqn? what does it show?
- weak acid/alkali
- partial ionisation
- reversible reaction
in which solution can acid ionise, and in which solution can acid not ionise?
Ionise in water
Does not ionise in anything else, including alcohol
If I have 10,000 HCL molecules and add water into it, how many H+ and Cl- ions there are?
10,000 H+ ions
10,000 Cl- ions
strong acid -> complete ionisation
ethanoic, nitric acid formulas
ethanoic: CH3COOH
nitric: HNO3
acids properties (6 pointers)
- sour taste
- conduct electricity in (aq) state
- turns blue litmus paper red
- turns Universal Indicator from green towards red
- corrosive when conc.
- pH 1-6
define acids
- substances that produce H+ ions when dissolved in water
1 Can acids/akali be solid?
2 Can acids/alkali be covalent compounds?
1 no.
2 yes!! Just need water
Example: Hydrogen chloride dissolves to become hydrochloric acid
1 Does Lead react with dilute HCl and H2So4?
2 Does Lead react with dilute nitric acid? HNo3?
1 Partially
2 Yes.
Why dosen’t lead react/not react with dilute HCl and H2SO4?
LINK
It partially reacts.
REASON
- insoluble layer forms, prevents further reaction
What is sulfuric acid used for? (2 uses)
- fertilisers, car batteries
What is ethanoic acid used for? (1 uses)
- manufacture vinegar
List 3 Strong and 1 Weak acid
Strong
Hcl, H2So4, HNo3
weak
- all organic acids
- e.g. CH3COOH
What does organic mean in Chem?
Anything with Carbon in the formula
What does organic mean in Chem?
Anything with Carbon in the formula
what is hydrochloric acid used for? (1 use)
remove rust -> clean metal surfaces
eqn. for Ionisation of HCl, H2So4, H3Po4. Given that H3Po4 is a weak acid, Which of the following is the most acidic?
HCl -> H+ + Cl
H2So4 -> 2H+ + SO42-
H3Po4 ⇌ 3H+ + Po43-
Most acidic
H2So4 (Sulfuric acid)
WHY?
Dibasic strong acid -> out of 100 H2So4, (2x100) H2 will be produced.
H3Po4 is weak acid -> out of 100 H3Po4, only maybe 3 H+ will be produced.
Clarification
Strength IS NOT mainly affected by basicity, but by the sign strong/weak acid
Define alkali
- Substance that produce OH- ions when dissolve in water
- Base soluble in water
alkalis to memorise
- aqueous ammonia nh3 (aq)
NH4 OH is rejected!! will penalise if write that. Use nh3 (aq) for aqueous ammonia
5 Properties of alkali
- bitter taste
- feel slippery
- conduct electricity in (aq) state
- turn universal indicator blue, indigo, violet
- pH 8-14
Are alkalis corrosive?
- Yes, for Conc. forms of strong alkalis
2 irl Uses of alkali
- toothpaste
- antacid
in neutral solution, what is the concentration of H+ ions and OH- ions?
Conc. of H+ ions = Conc. of OH- ions
Common misconception:
There are no ions -> THIS IS NOT TRUE!!
ACTUALLY, THERE ARE EQUAL CONC. OF H+ and OH- IONS
pH<7 means…?**
when pH<7, what can be concluded about conc. of H+ and OH- ions?
Fill in the blanks
The ___ the pH value, the ___ the conc. of H+ ions
conc. of H+ ions > conc. of OH- ions
Fill in the blanks
higher, lower or
lower, higher
What does pH actually measure?
- conc. of H+, OH- ions
when pH>7, what can be concluded about conc. of H+ and OH- ions?
H+ ions < OH- ions
alt. answer: OH- ions > H+ ions
conc. vs strength
conc: amt of dissolved substance
- can be changed
- dilute/conc.
strength: ease of dissociation of acid molecules
- every acid is fixed
- strong/weak
no such thing as “very strong”
olvl syllablus only “strong” or “weak”
which one reacts more?
X reacts readily to Y
Z reacts vigorously to Y
Z reacts more.
Vigorously > Readily in terms of reaction
Write the eqn. for ionisation of HOCL (Hypochlorous acid) given that it is a weak acid
HOCL ⇌ H+ + OCl-
Must add charges. This is ionisation
magnesium is a metal
weak acid vs strong acid
with same amount of H+ ions released upon dissolving in water
reaction w/ magnesium
differences, similarities
difference:
- weak acid releases lower conc., H+ ions
similarity:
- weak acid releases same vol of gas as strong acid (only if same amt of H+)
Which keywords signalises an alkali?
LINK:
Alkali is base that is soluble in water
ammonium/(grp1) oxide/hydroxide
ammonium vs ammonia full list of differences
nium
- only found in salt
- all states
nia
- base
- gas/(aq) state
- default state: gas
- NH3
LINK
- all bases can dissociate in water and will give out OH- (hydroxide ions)
I have weak acid X. What can I conclude about it?
- reactions, reversible
- undergo partial ionisation when dissolve -> water
Not all weak acids have Carbon inside of them, but all acids that are organic (have Carbon) are weak acids
How to identify Acidic oxides
All non-metal oxides
- So2, So3, SiO2 e.g.
except for
- NO, CO, H2O
no cold water
NO CO H2O
Define oxide?
compound formed from oxygen w/ other element/compounds
Any chemical formula containing oxygen
(can be o, O2, O3…)
How to identify Neutraic Oxides
NO
CO
H2O
No Cold Water
Does not apply to other higher subscript oxide formulas
i.e. CO is neutraic but Co2, Co3 isnt
i.e. NO is neutraic, but No2 isnt.
*unrelated: N2 is neutral (btw n2 isn’t an oxide, no oxygen in formula)
Acidic oxides
1 chem
2 phys
property
- React w/ alkali to form salt, water only
- usually GAS at r.t.p.
- soluble, water
acts like any other acid, can jst react with any other alkali.
Neutraic oxide properties
- does NOT react w acid/alkali
ALL ___ oxides are basic oxide?
all metal oxides are basic
- e.g. Na2O, MgO, Fe2O3…
except
Zn
Al
Pb
ZAP
Properties of basic oxides
- Usually solid in r.t.p.
- insouble in water except (Grp1) oxides
- react w/ acids, form salt+ water
Ammonium oxide does not exsist.
MISCONCEPTION
Base needs to dissolve to react.
Nope! It just dosen’t show alkali properties. Still will react.
Amphoteric Oxides
Zn
Al
Pb
ZAP
Properties of Amphoteric Oxides
- insoluble in water
- show both basic acidic properties
Zn
Al
Pb
(ZAP)
I have acid X2H. It is weak dibasic acid. The formula of X2H ion is X2H 2-. Explain why it is weak with a use of equation
X2H ⇌ X 2- + 2H+
Why 2H? It is dibasic
1H is +
2H is 2+
To balance out the 2-
does base need to dissolve to react with acid
MISCONCEPTION
Base needs to be (aq) to react
ACTUAL
Nope! Insol. base dosen’t show alkali properties. Still will react.
WHERE IS THIS USED IN?
i.e. excess solid reactant method
aq. acid + insoluble base
HOWEVER
acid needs to be (aq). Acid CANNOT be solid.
nitric acid
or
HCl
Stronger acid?
Nitric acid
Why Pb (lead) only react nitric acid?
- form insoluble layer, lead (II) sulfate / lead(II) chloride over reactants
