Acids And Alkalis

Question 1

what happens when an acid reacts with a base

Answer 1

They neutralise each other: acid + base —> salt + water

Question 2

What is the reactivity series

Answer 2

Please(potassium) Stop(sodium) lying(lithium), calling(calcium) me(magnesium) a(aluminium) careless(carbon) zebra(zinc) instead(iron) try(tin) learning(lead) how(hydrogen) copper saves(silver) gold platinum

Question 3

What are the 3 main acids

Answer 3

• Hydrochloric: HCl
• Sulfuric acid: H2SO4
• Nitric acid: HNO3

Question 4

Metal + acid —->

Answer 4

Metal + acid —> salt + hydrogen

Question 5

Metal oxide + acid

Answer 5

Metal oxide + acid —> salt + water

Question 6

Metal hydroxide + acid

Answer 6

Metal hydroxide + acid —> metal salt + water

Question 7

Metal carbonate + acid

Answer 7

Metal carbonate + acid —> metal salt + carbon dioxide + water

Question 8

Ammonia + acid

Answer 8

Ammonia + acid —> ammonium ions

Question 9

What is the symbol for hydroxide

Answer 9

OH(-1 charge)

Question 10

What is symbol for sulfate

Answer 10

SO4 (2- charge)

Question 11

What is symbol for Carbonate

Answer 11

CO3(2- charge)

Question 12

What is symbol for nitrate

Answer 12

NO3 (- charge)

Question 13

How do you make a soluble salt

Answer 13

• pick an acid and an insoluble base
• gently warm dilute acid using Bunsen burner
• turn it off
• add insoluble base to acid, wait for it to react
• Now there should be some excess left over
• filter out the excess to get the salt solution

Question 14

What pH does stomach acid typically have?

Answer 14

About 2

Question 15

The pH of a solution can be measured using a type of chemical dye that changes colour, depending on the pH of the substance it’s mixed with.

This chemical dye is usually referred to as:

Answer 15

Universal indicator

Question 16

Universal indicator is made up of….

Answer 16

• several different indicator solutions.
• This means that it undergoes a smooth colour change over a wide range of pH values.
• It becomes more red in colour in acidic solutions,
• but more bluey-purple in alkaline solutions.

Question 17

pH of pure water

Answer 17

7

Question 18

reasons why using a pH probe may be more reliable than using an indicator.

Answer 18

• A probe produces a more accurate result
• Determining the colour of an indicator is subjective

Question 19

A substance that forms an aqueous solution with a pH less than 7 is…

Answer 19

An acid

Question 20

What ion is responsible for making an alkaline pH when dissolved in solution

Answer 20

OH-

Question 21

When acid molecules are added to water and split apart, we say that they…

Answer 21

Ionise

Question 22

Do strong or weak acids completely ionise

Answer 22

• Strong acids ionise completely
• weak acids only partially ionise.

Question 23

Is the dissociation or ionising of weak acids a reversible reaction

Answer 23

Yes - the products can react together to reform the acid.

Question 24

For a weak acid, does the position of equilibrium lie to the left or the right?

Answer 24

Left

Question 25

Carbonic acid is described as a weak acid, explain why

Answer 25

• It does not fully ionise to release hydrogen ions
• It will form a solution with a pH of less than 7

Question 26

How do you describe the strength of acids

Answer 26

The proportion of acid molecules which dissociate into hydrogen ions

Question 27

The concentration of an acid refers to…

Answer 27

the number of moles of acid molecules per unit of volume.

Question 28

Is the strength of an acid is the same as its concentration.

Answer 28

No
- an acids strength refers to how well it ionises (dissociates) when added to water.
- its concentration refers to how many molecules there are per dm3 of solution.

Question 29

As the concentration of hydrogen ions in a solution increases, what happens to the pH?

Answer 29

The pH decreases

Question 30

What type of reaction is it when an acid and a base react together?

Answer 30

Neutralisation reaction

Question 31

What happens during neutralisation

Answer 31

During a neutralisation reaction, the positive hydrogen ions from the acid react with the negative hydroxide ions from the alkali to form molecules of water.

Question 32

How to obtain soluble salt crystals from an acid-base reaction

Answer 32

1) Place dilute acid in a beaker and heat gently.
2) Add the solid base bit by bit until it stops reacting, which means it’s in excess.
3) Isolate the salt solution by filtering out the excess solid base using filter paper and a funnel.
4) Heat the salt solution gently in a water bath until crystals start to form.
5) Let the solution cool further, which will cause more crystals to precipitate.
6) Filter out the soluble salt crystals using filter paper and funnel.

Question 33

When a soluble salt is formed from an acid and an insoluble base, how do you know when an excess of base has been added?

Answer 33

Some of the reactant will be left unreacted