Acids, Bases and Salts Flashcards
Define acids.
proton donors
Define bases.
proton acceptors
What type of ions do aqueous solutions of acids contain?
H+ ions
H+ ions are found in aqueous solutions of ________.
acids
What type of ions do aqueous solutions of alkalis contain?
OH- ions
OH- ions are found in aqueous solutions of ________.
alkalis
What are alkalis?
soluble bases
What are bases, in terms of its molecule?
oxide/hydroxide of a metal
What colour does litmus turn in an acid?
red
What colour does thymolphthalein turn in an acid?
colourless
What colour does methyl orange turn in an acid?
red
What colour does phenolphthalein turn in an acid?
colourless
What colour does litmus turn in an alkali?
blue
What colour does thymolphthalein turn in an alkali?
blue
What colour does methyl orange turn in an alkali?
yellow
What colour does phenolphthalein turn in an alkali?
pink
What is formed when a metal reacts with an acid?
hydrogen and a salt
In what reaction is hydrogen and a salt formed?
between a metal and acid
What is formed when metal carbonates react with acids?
a salt, carbon dioxide and water
In what reaction are a salt, carbon dioxide and water formed?
between a metal carbonate and an acid
What is formed when a base reacts with ammonium salts?
a salt, water and ammonia gas
Define a strong acid.
an acid that is completely dissociated in aqueous solution
Define a weak acid.
an acid that is partially dissociated in aqueous solution
Is hydrochloric acid weak or strong? What is an equation that proves this?
strong
HCl (aq) -> H+(aq) + Cl- (aq)
Is ethanoic acid weak or strong? What is an equation that proves this?
weak
CH3COOH (aq) -> H+ (aq) + CH3COO- (aq)
What is a reaction between an acid and an alkali?
neutralisation reaction
Why is water formed in a neutralisation reaction?
water, because the H+ ions and OH- ions form water
Most non-metal oxides are ______.
acidic
Are most non-metal oxides acidic or basic?
acidic
What are examples of acidic non-metal oxides?
SO2 and CO2
Most metal oxides are ______.
basic
Are most metal oxides acidic or basic?
basic
What are examples of basic metal oxides?
CuO and CaO
What are amphoteric oxides?
oxides that reacts with acids AND with bases to produce a salt and water
What are two examples of amphoteric oxides?
Al2O3 and ZnO
Al2O3 and ZnO are _________.
amphoteric oxides
Are sodium salts soluble or insoluble?
soluble
Are potassium salts soluble or insoluble?
soluble
Are ammonium salts soluble or insoluble?
soluble
Are nitrates soluble or insoluble?
soluble
Are chlorides soluble or insoluble?
soluble, except for lead and silver
Are sulfates soluble or insoluble?
soluble, except for barium, calcium, and lead
Are carbonates soluble or insoluble?
insoluble, except sodium, potassium and ammonium
Are hydroxides soluble or insoluble?
insoluble, except sodium, potassium, ammonium and calcium (partially)
What is/are the unit(s) for concentration?
g/dmˆ3 or mol/dmˆ3
How can you convert from mol/dmˆ3 to g/dmˆ3?
by multiplying mol/dmˆ3 by the Mr
Formula for concentration
concentration (mol/dmˆ3) = moles/volume (dmˆ3)
What are methods for preparing, separating and purifying SOLUBLE salts?
reacting an acid with:
an alkali in a titration
excess metal
excess insoluble base
excess insoluble carbonate
What is a method for preparing INSOLUBLE salts?
precipitation
The first part of a salt’s name comes from…
the metal part of the base
The second part of a salt’s name comes from…
the acid
What are the main three possible types of salts?
chlorides, sulfates, nitrates
What are the three main acids?
nitric acid
sulfuric acid
hydrochloric acid
What are the possible types of bases?
metal oxides
metal hydroxides
metal carbonates
ammonia
You use the _____ method to produce salts from reactions with an acid + _______/________/______
same
metal/metal oxide/metal carbonate
Describe how to produce salts using an acid and a metal/metal oxide/metal carbonate.
- warm acid to speed up reaction
- add excess of the metal to acid
- filter solution: removes excess solid
- transfer to evaporating dish
- use bunsen burner to evaporate water (around 2/3) until crystals start to form
- leave to cool
- filter to get crystals
- dry crystals on filter paper
Why do you add excess metal/metal oxide/metal carbonate when preparing a salt using an acid?
to ensure all acid has been neutralised
Describe how to carry out a titration.
- use volumetric pipette to measure known amount of acid in conical flask
- add a few drops of indicator
- fill burette with base
- add base to acid until colour change
- record volume added
- repeat w/o indicator
- transfer to evaporating dish and heat it
- leave to cool, filter and dry crystals
What is precipitation used for?
preparing insoluble salts
Describe how to carry out a precipitation.
- mix equal quantities of two soluble salts
- filter to remove insoluble salt (precipitate)
- wash precipitate with water
- leave to dry
Why should you rinse the burette with titrant after rinsing with water?
to avoid diluting the titrant
State the colour range of universal indicator and what they mean in relation to pH.
red/orange/yellow: acid
green: neutral
blue/purple: bases
What is a hydrated substance?
a substance that is chemically combined with water
What is an anhydrous substance?
a substance containing no water
Define the term ‘water of crystallisation’.
the water molecules present in hydrated crystals
In a universal indicator, the closer to _____, the more acidic it is.
red
In a universal indicator, the most basic solutions are ______.
purple