C5 Chemical Changes Flashcards
What is an oxidation reaction?
An reaction where something gains oxygen
What does “it has been oxidised mean”?
When it has gained oxygen
What does it mean if something has been reduced?
It has lost oxygen
What the PH scale?
Whta is a neutral (number
What is a low or high called
It measires how acidic somethig is
Goes from 0-14
The lower it is the more acidic it is
The higher it is the more alkaline it is
A neutral substance is a 7
What is the universla indicator?
Something (based on colors) that when added to a solution will react to form a colour which can be checked to see what acidity it is
How else could you calucate the acidity of something?
Using a PH probe
What is an acid?
A substance that formes an aq solution with a ph less that 7
What is an alkali??
A base that disloves in water tp form a solition with a PH value of more than 7 and which forms OH- ions in water
Give the reaction between acids and base:
Acid+Base = Salt+Water
Or it could be said like this
H+(aq) + OH-(aq) = H*2O(l)
What do acids produce in water?
Protons
Hydrogen ions (which is the same as a proton)
What dp acids do in a aq solution?
They ionise
Of an alkali as solution reacts with a acid then what is alwayes formed
OH-ions
What is the equation for neutralisation?
H+(aq)+ OH-(aq)=H2O(l)
Acid+Alkali
Acid+Alkali=Salt + Water
Acid+Metal carbonate
Acid+Metal carbonate = Salt+ Water+Carbon Dioxide
What is a PH probe?
Attacked to a PH meter it can also measure the PH of a substance electronicly and really acuratly. It will give you a number.
What do acids produce in water?
They ionise in an aq solution and produce H+ ions
What happens when a strong acid meets water?
It ionise completely. All the acid particles dissociate to release H+ ions
Give 3 examples of a strong acid?
Sulfuric, hydrochloric and nitric acids
What happens when a week acid meets water?
It doesn’t fully ionise. Only a small portion of the acid particles dissociate to release H+ ions
Give 3 examples of a week acid?
Ethanoic, citric and carbonic acids
When a week acid is ionised can it be reverced?
When a strong acid is ionised can it be reverced?
Yes as only a few of the acid particles ionised
No as all of the acids ionised
Why are strong acids more reactive than week acids?
The reaction is with H+ ions and other substances. So if the concentration of H+ ions is bigger (eg in strong acids) then there will be a quicker and more reactive
What exactly is the PH of a substance measuring?
The amout of H+ ions in a solition