Acids Flashcards
What is formed when a metal and an acid react?
Salt and hydrogen
What is formed when an acid and a metal oxide react?
Salt and water
What is formed when an acid and a metal hydroxide react?
Salt and water
What is formed when an acid and a carbonate react?
Salt + Water + Carbon dioxide
What is formed when an acid and ammonia react?
Ammonium salt
What is the difference between a base and an alkali?
- An alkali is a base that is soluble in water
- Often these are hydroxides bound to group 1 or 2 metals
- Ammonia (NH3) is also an alkali
Definition of an acid (Bronsted and Lowrey)
An acid is a proton (H⁺) donor
Definition of a base (Bronsted and Lowrey)
A base is a proton (H⁺) acceptor
What is a neutralisation reaction?
A neutralisation reaction is when a base is added to an acid to form a salt and water
Acid + Base -> Salt + Water
What is an ionic equation?
The simplification of reactions
What will always be the ionic equation for a neutralisation reaction?
H⁺ (aq) + OH⁻ (aq) –> H₂O
What will acids and alkalis do when added to water?
Breakdown into their ions / ionise
What do acids release when added to water?
H⁺ ions (aq)
What do alkalis release when added to water?
OH⁻ ions (aq)
What is the pH scale?
A measure of the concentration of H⁺ ions
How does strength of acid affect pH?
The stronger the acid, the higher the concentration of H⁺ ions and the lower the pH
What is the difference between strong and weak acids
Strong acids completely ionise, whereas weak acids only partially ionise
What is the relationship between pH and H⁺ ion concentration?
For every ten fold dilution of a strong acid, the pH value increases by 1
For every ten fold increase in concentration of a strong acid, the pH value decreases by 1
What is a dilute acid?
A small amount of acid dissolved in a large amount of water
What is a concentrated acid?
A large amount of acid dissolved in a small volume of water
Making a salt using an insoluble base method
- Measure approximately 40cm3 of the acid (specify) into a 100cm3 beaker
- Heat the acid gently using the Bunsen burner, tripod, gauze and heatproof mat until it is about 70 degrees Celsius
- Add the base (specify) one spatula at a time, stirring with a glass rod
- Continue to add until the base is in excess
- Set up a filter funnel and paper over a conical flask. Filter the reacted acid and base
- When the filtration is complete, pour the filtrate into an evaporating basin.
- Heat this gently using a water bath and stop heating when crystals start to form
- Leave to crystallise
- Gently pat the crystals dry between two pieces of filter paper
Making a salt using an alkali method
- Rinse a burette first with distilled water and then with the acid (specify). Discard the solution used
- Measure 25cm3 of the alkali (specify) and transfer to a conical flask
- Add 3 drops of methyl orange indicator to the flask
- Fill the burette with dilute hydrochloric acid and make sure there are no air bubble near to the jet
- Take the initial volume of the acid in the burette. Add the acid to the sodium hydroxide solution in the conical flask, swirling the flask all the time, until the indicator changes colour. Take the final volume of the acid
- Repeat the titration until two of your readings agree to within 0.10 cm3
- Repeat the titration without methyl orange indicator
- Transfer solution to an evaporating basin, heating partially to evaporate water. Stop heating when crystals start to form
- Leave to crystallise
- Gently pat the crystals dry between two pieces of filter paper
