C3.3 Types Of Chemical Reaction Flashcards
What is a redox reaction?
A redox reaction is a reaction in which reduction and oxidation happen at the same time.
What is a half equation?
A half equation shows the change that happened to one reactant in a reaction.
What is a base?
A base is a substance,musically a metal oxide or metal hydroxide, that can neutralise acids.
If a base can dissolve in water, it is also an alkali
What is an alkali?
An alkali releases hydroxide ions when it dissolves in water.
Define concentration
Concentration measures how much acid there is in a litre
(1 dm^3) of water
On a pH scale, what is neutral? What is acidic? What is alkaline?
pH < 7 means acidic
pH = 7 means neutral
pH > 7 means alkaline
Describe how to use a pH meter
Wash the pH probe with water, then put it into a calibration buffer.
Adjust the reading to match the pH of the buffer solution
To measure the pH of a solution, wash the probe with water and then put it into the solution.
You should wash the probe with water between each measurement to make sure that the probe with water between each measurement to make sure that the probe isn’t contaminated with the previous sample as this would affect the reading
Acid + Alkali ->
Salt + water
Acid + metal ->
Salt + hydrogen
Define the term ‘neutralisation’.
Neutralisation is the reaction between an acid and a base, or an alkali, to form a salt and water only.
What type of salts does sulfuric acid produce?
Sulfate salts
Weak acid
Weeks acids (eg. Ethanoic, citric and carbonic acids) partially ionise in solution. Only a small proportion of acid molecules dissociate to release hydrogen ions. Their pHs tend to be around 2-6.
Define the term ‘carbonates’.
Carbonates are ionic compounds that contain the carbonate ion.
What type of salts does hydrochloride acid produce?
Chloride salts
Define the term ‘effervescence’
Bubbling or fizzing
What is a dilute acid?
A dilute acid contains a low ration of acid to volume of solution
What does acid strength tell you?
Acid strength tells you what proportion of the acid molecules ionise in water.
Ionisation of weak acids reversible?
The ionisation of a weak acid is a reversible reaction, which sets up an equilibrium mixture. Since only a few of the acid molecules release hydrogen ions, the equilibrium lies well to the left.
Strong acid
Strong acids (eg. Sulfuric, hydrochloric and nitric acids) fully ionise in water. A large proportion of acid molecules dissociate to release hydrogen ions. They tend to have low pHs (0-2)
In aqueous solution, as the concentration of hydrogen ions increases by a factor of 10,
the pH of a solution decreases by 1
What is a pH titration curve?
A pH tritration curve shows the effect on pH of changin hydrogen ion concentration during a nupeutralisation reaction
Acid + Metal carbonate ->
Salt + water + carbon dioxide
What is the end point of the tritration?
It is the vertical point in the pH tritration curve where the solution is neutral.
What is an acid?
An acid is a substance that releases hydrogen ions when it dissolves in water to make an aqueous solution.
What is a concentrated acid?
A concentrated acid contains a high ratio of acid to volume of solution.
Lower pH than a dilute acid
When an acid neutralises a base (or vice versa)…
…the concentration of hydrogen ions equals the concentration of hydroxide ions.
How to make insoluble salts? Eg. Lead chloride
Add 1 spatula of lead nitrate to a test tube. Add deionised water to dissolve the lead nitrate. Use deionised water to make sure there are no other ions about. Shake it throughly to ensure that all the lead nitrate has dissolved.
Then, in a separate test tube, do the same with one spatula of sodium chloride.
Tip the two solution into a small beaker, and give it a good stir to make sure it’s all mixed together. The lead chloride should precipitate out.
Put a folded piece of filter paper into a filter funnel, and stick the funnel into a conical flask.
Pour the contents of the beaker into the middle of the filter paper. Make sure that the solution doesn’t go above the filter paper - otherwise some of the solid could dribble down the side.
Swill out the beaker with more deionised water, and tip this into the filter paper - to make sure you get all the wanted products from the beaker.
Rinse the contents of the filter paper with deionised water to make sure that all the soluble sodium nitrate has been washed away.
Then just scrape the lead chloride onto fresh paper and leave to dry.
