Acids, alkalis, salt preparation

Question 1

pH of acids

Answer 1

1-6

Question 2

Neutral pH (water)

Answer 2

7

Question 3

pH of alkalis

Answer 3

8-14

Question 4

What is an indicator

Answer 4

A dye that changes colour depending on a pH

Question 5

Name an indicator

Answer 5

Universal Indicator

Question 6

What does litmus paper do and what pH does it change colour at

Answer 6

Determines whether a solution is acidic or alkaline because it changes colour at a pH of around 7

Question 7

What colour does litmus paper turn in acidic solutions

Answer 7

Red

Question 8

What colour does litmus paper turn in neutral solutions

Answer 8

Purple

Question 9

What colour does litmus paper turn in alkaline solutions

Answer 9

Blue

Question 10

Phenolphthalein will change from what in acidic solutions to what in alkaline solutions

Answer 10

Colourless (acidic) to bright pink (alkaline)

Question 11

What is an acid

Answer 11

A source of hydrogen ions, proton donors and pH less than 7

Question 12

What is a base (alkalis)

Answer 12

Proton acceptors, they are soluble bases and a source of hydroxide ions, pH greater than 7

Question 13

What can bases (alkalis) do?

Answer 13

Neutralise acids

Question 14

What is the reaction between a base (alkalis) and a acid called

Answer 14

A neutralisation reaction

Question 15

How does a salt form

Answer 15

When acids react with bases

Question 16

What does the reaction of a base and salt form

Answer 16

A salt + water

Question 17

Acid + Metal oxide —>

Answer 17

Salt + water

Question 18

Acid + metal hydroxide —>

Answer 18

Salt + water

Question 19

Acid + ammonia —>

Answer 19

ammonia salt

Question 20

When else can salts form

Answer 20

When an acid reacts with a metal or a metal carbonate

Question 21

What are used to find out concentrations

Answer 21

Titrations

Question 22

What is the method for a titration

Answer 22

Using a pipette, add some alkali (usually about 25 cm³) to a conical flask, along with two or three drops of indicator.

Fill a burette with the acid.
Make sure you do this BELOW EYE LEVEL — you don’t want to be looking up if some acid spills over.

Using the burette, add the acid to the alkali a bit at a time — giving the conical flask a regular swirl. Go especially slowly when you think the end-point (colour change) is about to be reached.

The indicator changes colour when all the alkali has been neutralised,

Record the volume of acid used to neutralise the alkali.

Question 23

How you make a salt depends on what

Answer 23

Whether it insoluble or soluble

Question 24

If a salt is insoluble it will form as…

Answer 24

a precipitate

Question 25

A soluble salt forms as a...

Answer 25

solution