C3.3 Types Of Chemical Reaction

Question 1

What is a redox reaction?

Answer 1

A redox reaction is a reaction in which reduction and oxidation happen at the same time.

Question 2

What is a half equation?

Answer 2

A half equation shows the change that happened to one reactant in a reaction.

Question 3

What is a base?

Answer 3

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

Question 4

What is an alkali?

Answer 4

An alkali releases hydroxide ions when it dissolves in water.

Question 5

Define concentration

Answer 5

Concentration measures how much acid there is in a litre

(1 dm^3) of water

Question 6

On a pH scale, what is neutral? What is acidic? What is alkaline?

Answer 6

pH < 7 means acidic
pH = 7 means neutral
pH > 7 means alkaline

Question 7

Describe how to use a pH meter

Answer 7

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

Question 9

Acid + Alkali ->

Answer 9

Salt + water

Question 10

Acid + metal ->

Answer 10

Salt + hydrogen

Question 11

Define the term ‘neutralisation’.

Answer 11

Neutralisation is the reaction between an acid and a base, or an alkali, to form a salt and water only.

Question 12

What type of salts does sulfuric acid produce?

Answer 12

Sulfate salts

Question 13

Weak acid

Answer 13

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.

Question 14

Define the term ‘carbonates’.

Answer 14

Carbonates are ionic compounds that contain the carbonate ion.

Question 15

What type of salts does hydrochloride acid produce?

Answer 15

Chloride salts

Question 15

Define the term ‘effervescence’

Answer 15

Bubbling or fizzing

Question 16

What is a dilute acid?

Answer 16

A dilute acid contains a low ration of acid to volume of solution

Question 18

What does acid strength tell you?

Answer 18

Acid strength tells you what proportion of the acid molecules ionise in water.

Question 19

Ionisation of weak acids reversible?

Answer 19

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.

Question 20

Strong acid

Answer 20

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)

Question 21

In aqueous solution, as the concentration of hydrogen ions increases by a factor of 10,

Answer 21

the pH of a solution decreases by 1

Question 22

What is a pH titration curve?

Answer 22

A pH tritration curve shows the effect on pH of changin hydrogen ion concentration during a nupeutralisation reaction

Question 23

Acid + Metal carbonate ->

Answer 23

Salt + water + carbon dioxide

Question 24

What is the end point of the tritration?

Answer 24

It is the vertical point in the pH tritration curve where the solution is neutral.

Question 25

What is an acid?

Answer 25

An acid is a substance that releases hydrogen ions when it dissolves in water to make an aqueous solution.

Question 25

What is a concentrated acid?

Answer 25

A concentrated acid contains a high ratio of acid to volume of solution.
Lower pH than a dilute acid

Question 26

When an acid neutralises a base (or vice versa)…

Answer 26

…the concentration of hydrogen ions equals the concentration of hydroxide ions.

Question 27

How to make insoluble salts? Eg. Lead chloride

Answer 27

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.