Acids And Bases N5 U1 P5 Flashcards
What does the pH scale indicate, and determines
Acidic, neutral or alkaline
The ratio of hydrogen ions to hydroxide ions
Ph of neutral solutions
Water contains an equal concentration of H+ AND OH-, pH of 7
Ph of acidic solutions
Sources of H+ ions
pH below 7
PH of alkaline solutions
Sources of OH- ions
pH above 7
Water and neutral solutions
H2O[l] = H+[aq] +OH-[aq]
Only a few water molecules dissociated into free ions
= indicates the reaction is reversible
Dilution of acids and alkali reaction
Dilution can be tracked using a chemical indicator
Alkali added to acid, becomes more alkaline
Acid added to alkali, becomes more acidic
Forming acids and alkali
Formed by dissolving different oxides in water
Formation of acids
Soluble non-metal oxides dissolves in water
Non-metal oxide+ water -> acid
Formation of alkali
Soluble metal oxides or hydroxides dissolve in water
Metal oxide+ water -> alkali
Formation of a base
Neutralises an acid
Insoluble metal oxides, hydroxides or carbonates
All alkalis are bases, but not all baes are alkalis
Neutralisation reaction
Base reacts with acid to form water and salt
Acid+base= salt+water
Naming salt- sodium hydroxide and hydrochloric acid
Base- sodium hydroxide
Base is the salt name start- sodium
Acid- hydrochloric acid
Acid is salt name end- chloride
Neutralisation of an acid
Adding an alkali to an acid will increase the pH to 7
Neutralisation of an alkali
Adding an acid to an alkali will decrease the pH towards 7
Neutralisation reactions- different bases
Metal oxide+acid->salt+water
Metal hydroxides+acids->salt +water
Metal carbonates+acid->salt+water+carbon dioxide
Spectator ions
Present in the equation but remain chemically unchanged
Reacting species shown by removing spectator ions
Spectator ion equation- metal oxides
2H+[aq]+O2[s]->H2O[l]
Spectator ion equation- metal hydroxides
H+[aq]+OH-[aq]->H2O[l]
Spectator ion equations- aqueous metal carbonates
2H+[aq]+CO3,2-[aq]->H2O[l]+CO2[g]
Spectator ion equation- insoluble metal carbonates
2H+[aq]+CO3,2-[s]->H2O[l]+CO2[g]
Titration experiment
Unmeasured volume of one solution is added to a known volume of another solution until neutral
Indicator
Repeated until concordant results
Produce a soluble salt
Titration apparatus
Burette and pipette
When drawing apparatus burette must have graduation marks
Pipette has one graduation mark as is measures one volume
Titration calculations
Has to be a balanced chemical equation
1- data box- acid and base
2-calculate known quantity n over cv
3- identify mole ratio
4- calculate c1V1=c2V2
n1 n2
No.1 divide by no.2= c2[unkown concentration]
