Chemical Changes Flashcards
What do acids form in water?
H+ ions
What is a base?
A substance that reacts with an acid to produce a salt and water
Oxides and hydroxides
What do alkalis form in water?
OH- ions
What happens to the pH when the concentration of hydrogen ions increases?
The pH decreases
What happens to the pH when the concentration of OH- ions increases
The pH increases
What colour is litmus in:
Acid?
Neutral?
Alkali?
Acid: red
Neutral: purple
Alkali: blue
What colour is methyl orange in:
Acid?
Neutral and alkali?
Acid: red
Neutral and alkali: yellow
What colour is phenolphthalein in:
Acid and neutral?
Alkali?
Acid and neutral: colourless
Alkali: pink
What is the concentration of an acid?
How watered down it is
What happens to the pH if the concentration of H+ ions increases by a factor of 10?
It decreases by 1
What is the gas test for chlorine?
Damp blue litmus paper turns red then bleaches white
What is the what is the gas test for oxygen?
Glowing splint relights
What is the gas text for carbon dioxide?
Limewater goes cloudy
What is the gas test for hydrogen?
Lit splint in hydrogen makes squeaky pop
How do you make a soluble salt?
Acid + insoluble base
How do you make an insoluble salt?
Soluble salt + soluble salt
What are the 5 steps of titration?
- Measure out acid into conical flask and add indicator
- Slowly add alkali using burette until the indicator changes colour
- Redo the reaction without the indicator
- The solution now only contains salt and water
- Evaporate the water
What is electrolysis?
The breaking down of a substance using electricity
What is a positive ion called?
Cation
What is a negative ion called?
Anion
What is a positive electrode called?
Anode
What is a negative electrode called?
Cathode
What is electrolyte?
The liquid which carries the charges
What current is used for electrolysis?
Direct current
What does OILRIG stand for?
Oxidation Is Loss (of electrons) Reduction Is Gain (of electrons)
What happens to anions at the anode?
They are oxidised
Where are non metals discharged in electrolysis?
At the anode
What happens to cations at the cathode?
They are reduced
Where are metals discharged in electrolysis?
The cathode
Why is electrolysis easier with a molten electrolyte?
Because there are no H+ or OH- ions
Why is electrolysis harder with aqueous solutions?
Because it contains H2O/H+ and OH- ions
Are ‘all common sodium, potassium and ammonium salts’ soluble or insoluble?
Soluble
Is silver chloride soluble or insoluble?
Insoluble
Are all nitrates soluble or insoluble?
Soluble
Are
Lead sulphate
Barium sulphate
Calcium sulphate
Soluble or insoluble?
Insoluble
Are most chlorides soluble or insoluble?
Soluble
Are most carbonates soluble or insoluble?
Insoluble
Are
Sodium carbonate
Potassium carbonate
Ammonium carbonate
Soluble or insoluble?
Soluble
Are most hydroxides soluble or insoluble?
Insoluble
Are
Sodium hydroxide
Potassium hydroxide
Ammonium hydroxide
Soluble or insoluble?
Soluble
