Shells Chemistry Flashcards
What two chemicals are used to test for the presence of water and what colour change is seen if water is there?
Anhydrous copper sulphate goes from white to blue Cobalt chloride goes from blue to pink
What is the percentage of oxygen in the air?
21%
What is the percentage of nitrogen in the air?
78%
What is the percentage of carbon dioxide in the air?
0.03%
Approximately 1% of the air is made up of “other gases” what are these gases?
Mainly argon and water vapour
What is the reactivity series for metals? From most to least reactive (include hydrogen and carbon).
Potassium, sodium, (lithium), calcium, magnesium, aluminium, carbon, zinc, iron, tin, lead, hydrogen, copper, silver, gold, platinum.
What is the name given to the type of reaction where a more reactive element pushes a less reactive on from a compound?
Displacement reaction.
What is used to test whether a liquid is acidic or alkali?
Universal indicator paper or litmus paper
What colour does litmus paper go in acid?
red
What colour does litmus paper go in alkali?
Blue
What colour does universal indicator go in weak acid (pH 5-6)?
Yellow
What colour does universal indicator go in medium alkali (pH 10-11)?
Blue
What is the pH of a strong acid?
1 or 2
What is the pH of a strong alkali?
13 -14
Vinegar is a medium acid, what colour would it go in universal indicator?
Orange
Magnesium oxide dissolves to make a weak alkali solution, what colour will it go in universal indicator?
blue
The liquid from wasp stings turn universal indicator blue. What does this tell us about the pH of the liquid. What could be used to neutralise it?
It is alkali and could be neutralised by a weak acid e.g. vinegar.
What colour would you expect universal indicator to go in juice from a human stomach?
Red
Is boiling easily reversed?
yes
Is melting easily reversed?
yes
Is neutralisation easily reversed?
no, it is a chemical reaction
What gas is formed when metals react with acids or when more reactive metals react with water?
hydrogen
How do you test to prove that a gas is hydrogen
A lit splint gives a squeaky pop.
How do you test to prove that a gas is carbon dioxide?
Limewater turns from clear to cloudy when carbon dioxide is passed through it.
How do you test to prove a gas is oxygen?
It will relight a glowing splint.
What is a fuel?
A substance (normally a hydrocarbon) which is burned to release energy.
Give the word equation for complete combustion of a hydrocarbon fuel.
hydrocarbon+oxygen –> carbon dioxide + water + energy
What is formed when there is not enough oxygen for complete combustion of a fuel?
carbon monoxide + carbon (soot) + water
Sodium reacts with water, what two other metals did we see behave in a similar way?
Potassium and lithium (alkali metals, group 1)
What is meant by the pH of a liquid?
How acidic or alkaline it is.
What is an element?
A substance containing only one type of atom.
What is a compound?
A substance containing two or more types of atom chemically bonded together.
Carbonates break down when heated strongly. What name is given to this type of reaction?
thermal decomposition
What gas is released when carbonates are thermally decomposed?
Carbon dioxide
What would you expect to happen to the mass of a carbonate as it is heated?
It will decrease as carbon dioxide is released.
What do iron, magnesium and sodium have in common?
They are all metals so they all conduct electiricy and are shiny.
What pH woul dyou expect water to be? What does this mean?
pH 7 - neutral
