Acids, Alkalis and Indicators

Question 1

Describe the pH scale

Answer 1

The pH scale goes from 0 to 14, 0 being the most acidic and 14 being the most alkaline. The lower the pH the more acidic and the higher the pH, the more alkaline. 7 is a neutral pH as it is in the middle of the pH scale.

Question 2

What are indicators

Answer 2

Indicators are substances that change colour depending on pH. Universal indicator contains a mixture of different indicators, therefore it produces a range of colours depending on the pH

Question 3

What is the colour of Litmus in alkaline

Answer 3

Blue

Question 4

What is the colour of Methyl orange in alkaline

Answer 4

Yellow

Question 5

What is the colour of phenolphthalein in alkaline

Answer 5

Pink

Question 6

What is the colour of Litmus in acid

Answer 6

Red

Question 7

What is the colour of Methyl orange in acid

Answer 7

Red

Question 8

What is the colour of phenolphthalein in acid

Answer 8

Colourless

Question 9

When acids dissolve in water, what do they produce an excess of

Answer 9

Hydrogen ions ( h+)

Question 10

When alkalis dissolve in water, what do they produce an excess of

Answer 10

Hydroxide ions( OH-)

Question 11

What does it mean when there is a concentration of hydrogen ions in a substance

Answer 11

It is more acidic and has a lower pH

Question 12

What does it mean when there is a concentration of hydroxide ions in a substance

Answer 12

It is more alkaline and has a higher pH

Question 13

What does concentration mean

Answer 13

The amount of solute ( usually measured in grams) dissolved in a certain volume of solvent.

Question 14

What does dissociate mean

Answer 14

Break up

Question 15

What is the formula for concentration

Answer 15

Concentration ( g/ dm^3) =

Volume of solution (dm^3)

Question 16

How do you convert cm^3 to dm^3

Answer 16

Cm^3 to dm^3 = Divide 1000

Question 17

How do you convert dm^3 to cm^3

Answer 17

Dm^3 to Cm^3 = Multiply 1000

Question 18

What does a dilute solution mean

Answer 18

Contains only small amounts of dissolved solute per unit volume

Question 19

What does a concentrated solution mean

Answer 19

Contains a lot of dissolved per unit volume

Question 20

What happens to pH when H+ ions increase by a factor of 10

Answer 20

pH decreases by 1

Question 21

What happens to pH when H+ ions decrease by a factor of 10

Answer 21

pH increases by 1

Question 22

What are strong acids

Answer 22

Strong acids fully dissociate when they dissolve in water. This produces high concentrations of H+ ions and therefore a lower pH value

Question 23

What are weak acids

Answer 23

Weak acids only partially dissociate when they dissolve in water. This means not all of their molecules will be split, so only a low concentration of H+ ions is produces, therefore a higher pH