Paper 6 Flashcards
When a the gas collecting tube is upside down, give a property of this gas
It is less dense than air
Why is a pencil used in drawing the origin line in chromatography?
If pen was used it will dissolve giving colors and so the experiment won’t be accurate
When using ethanol, give a better apparatus arrangement, and why?
Cover apparatus with a lid bc ethanol is volatile
In tests and observation tables, when in the first row, they tell upon heating condensation occurred, there will be a question asking what does this show about the solid?
It is hydrated
When copper is used in a test
Light blue precipitate which is soluble in excess to form dark blue solution
Why is the experiment done in a fume cupboard?
It releases harmful gases that are poisonous and toxic
Why should the solid be crushed?
It increases surface area for a faster rate if reaction
Why is the experiment made in a well-ventilated room?
To prevent the burning of a substance
Explain the term decant
Filter/pour liquids leaving solid alone
Why is concentrated sulphuric acid not used to dry ammonia ?
Because it will react with the base ammonia, which is a neutralization reaction
Why should samples be taken from different parts of the field?
To get more accurate results
Suggest why it is important to know the ph of the soil
To see which is the best place for growing and what kind of base to use for neutralizing it
What is necessary for rusting?
Water(humidity) and oxygen (air)
Suggest why in an experiment for rusting the water level increases
Oxygen is used up and water is used to take its place
For electrolysis, state the observations
The bulb will light, a metal is formed at the cathode, fizz if gas is produced
Suggest suitable materials for electrodes
Graphite
Carbon
Steel
When copper is reacted with hydrogen , what is the colour change?
Black to brown because copper oxide is reduced to copper
How can you distinguish between water and ethanol?
Use cobalt chloride paper, it turns from pink to blue with water, but no change with ethanol
How can you distinguish between sulphuric acid and aqueous sodium sulphate?
There are three tests.
- You can use a metal carbonate in Which Co2 will be produced with sulphuric acid but there will be no change with sodium sulphate
- You can add a metal which hydrogen is produced with sulphuric acid, but no change with sodium sulphate
- Use an indicator like litmus paper. With sulphuric acid with will turn red. With sodium sulphate there is no change
How can you distinguish between hydrochloric acid and nitric acid ?
Add silver nitrate in which white ppt will be formed with hydrochloric acid. But there is no reaction with nitric acid
What is he purpose of the mineral wool?
To absorb and hold the liquid
When there is a delivery tube involved in a question, what precaution should be taken in the experiment when the heat is removed?
Remove the delivery tube to prevent suck- back
How can you distinguish between an alkanes and alkenes?
Use bromine water , in Alkene it will go colour less. In an Alkane it will remain orange
How can you distinguish between chlorine and sodium chloride?
Add litmus paper, it will bleach with chlorine but nothing happens with sodium chloride
How can you distinguish between copper sulphate and copper carbonate?
Acidify with hydrochloric acid, and add barium chloride, there will be a white ppt with sulphate but no white ppt with carbonate
OR just add hcl in which nothing happens with sulphate, but fizz or effervescence of co2 will occur with carbonate
When a measuring cylinder is used how could you change the apparatus for more reliable results?
A biuret can be used instead
What happens if the reagent is more concentrated
Volume if reagent decreases if it is more concentration
Concentrated acid
An acid that contains a large number of H+ hydrogen ions. Vice versa with dilute acid
Concentrated base
A base that contains a large number of OH- hydroxide ions. Vice versa with a dilute base
Strong acid
And acid that ionizes completely giving H+ in solutions. Vice versa with a weak one
Strong base
Is one that ionizes completely giving OH- in solutions. Vice versa for a weak base
Concentrated
A solution that contains a large number of solute or little amount of water is involved.
How can crystals be made?
- Heat till point of crystallization
- Leave to cool gradually
- Filter, dry and collect crystals
How can you detect the point if crystallization?
Place a stirring rid in the solution and see the formation if the first crystals on it
What is the purpose of ice or cold water?
To cool down the gas so that it condenses and turns into liquid
