Indicators, Acids and Alkalis

Question 1

define an indicator and give an example of one

Answer 1

an indicator is a substance that tells us whether a substance is either acidic or alkaline e.g. litmus paper, universal indicator

Question 2

describe how to make red cabbage indicator

Answer 2

1. Cut the cabbage into small parts.
2. Place the chopped cabbage into the pot and cover with water.
3. Boil until the water is a deep purple.
4. Strain the leaves out, and the remaining liquid is your cabbage pH indicator.

Remember that it will turn pink/red if it is acidic and green/yellow if it is an alkali

Question 3

know what the pH scale is and where to find what

Answer 3

a way of measuring how acidic or alkaline a substance is

7 is neutral
0 is acid
14 is alkaline

Question 4

neutralisation reactions - reactants and products

Answer 4

when acids are able to cancel out alkaline and vice-versa (it becomes neutral)

they produce salt and water

Question 5

uses of neutralisation

Answer 5

liming soil
antacid tablets
making bee-stings less painful

Question 6

what is an example of a base and what can some do and give an example

Answer 6

metal oxides

some bases can dissolve in water to form hydroxides (alakalis)

e.g. calcium oxide -> (alkali) calcium hydroxide

Question 7

what can carbonates do

Answer 7

make salts

Question 8

how do you name it when base neutralizes and becomes a salt

Answer 8

you name it with the first name of the first substance and the second substance’s first word and that goes second

e.g. copper oxide + sulphuric acid -> copper sulfate + water

Question 9

what do all carbonates do when added to acids

Answer 9

make CO2

Question 10

how do metals reacts with acids

Answer 10

they form salt and hydrogen

Question 11

what is the test for CO2

Answer 11

bubble it through limewater and it will turn milky from colourless

Question 12

what is the test for hydrogen

Answer 12

light a splint
if there is hydrogen, you will hear a squeaky pop

Question 13

define acid rain and describe how it is formed by the burning of fossil fuels

Answer 13

• acid rain is rain with a pH of below 7
• it is formed when carbon dioxide from the burning fossil fuels get dissolved with the water

Question 14

list the effects of acid rain

Answer 14

• it can cause a chemical reaction to take place (if it falls on limestone) - it can erode buildings too and this is called limestone weathering

Question 15

what is the equation for metal carbonates and acids

Answer 15

metal carbonate + acid -> salt + water + carbon dioxide

e.g. copper carbonate + sulphuric acid -> copper sulphate + water + carbon dioxide