C1.3 Flashcards
What are hazard symbols and what do they mean?
oxidising - provides oxygen and allows other materials to burn more easily
e.g liquid oxygen
highly flammable - catches fire easily
e.g petrol
toxic - can cause death if swallowed, breathed in or absorbed through skin
e.g hydrogen cyanide
harmful - like toxic but not as dangerous
e.g copper sulphate
irritant - not corrosive but can cause reddening or blistering of the skin
e.g bleach
corrosive - attacks and destroys living tissues including eyes and skin
e.g concentrated sulphuric acid
What 3 things can substances be?
acids, bases or neutral
What is the PH scale?
a measure of how acidic or alkali a substance is
0-3 - strong acid, red 4-6 - weak acid, yellow/orange 7 - neutral, green 8-10 - weak alkali, blue 11-14- strong alkali - purple
What do reactions between acids and bases make?
acids and bases react together to form a salt and water
products are neutral so called a neutralisation reaction
What can salts produced in neutralisation reactions be used for?
fertilisers - ammonium nitrate
fireworks, as colouring agents - calcium chloride )orange), copper chloride (bluey-green)
What acid is produced in the stomach and why?
What happens if there is too much?
hydrochloric acid
enzymes that break down food work best in acidic environments
helps kill bacteria and reduces chance of food poisoning
too much can cause indigestion
indigestion tablets contain bases e.g calcium carbonate that neutralises the excess acid
How do you know what indigestion tablet is best?
crush up the tablets you want to test
add a bit of acid at a time and an indicator
the tablet which needs most acid to neutralise it is the best indigestion cure as it will neutralise the most excess acid in the stomach
What are the equations for metal, acid, salt combinations?
hydrochloric acid produces a chloride
sulphuric acid produces a sulphate
nitric acid produces a nitrate
What is the equation for reactions involving metal carbonates?
an acid+ metal carbonate - salt + water + carbon dioxide
What is electrolysis?
splitting up with electricity
breaking down compounds using electrical energy
What is needed for electrolysis ?
liquid - to conduct electricity
electrolyte - contains the compound broken into component parts
electrodes - apply electricity to electrolyte
How can hydrochloric acid be electrolysed?
electrode- dilute solution of HCL
apply DC current- causes it to decompose into component parts
gases bubble through solution and collect at electodes
What are the products when you electrolyse hydrochloric acid?
hydrogen and chlorine
What does electrolysis of salt produce?
chlorine
sodium chloride solution decomposed using electrolysis
What are the uses of chlorine?
treat water supplies - kills bacteria and microbes
bleach manufacture
to make the polymer poly(chloroethene)
What does electrolysis of water produce?
hydrogen and oxygen
How can you test for gases?
oxygen - glowing splint, oxygen relights it
hydrogen - ‘squeaky pop’ with lighted splint (hydrogen burning with oxygen in air produces noise)
chlorine - damp blue litmus paper, it turns it red before bleaching it
carbon dioxide - turns limewater cloudy
