acids and bases & titration Flashcards
acid
substance that releases H+ ions in an aqueous solution (a proton donor)
base
substance that removes H+ ions from an aqueous solution (a proton acceptor)
strong acid
an acid that almost completely ionises/dissociates in an aqueous solution
weak base
a base that only slightly ionises/dissociates in an aquous solution
salt formed by the acids: hydrochloric acid, sulfuric acid, nitric acid
chloride, sulfate, nitrate
product formed when an acid reacts with a base
a salt and water
product formed when an acid reacts with a metal carbonate
a salt, carbon dioxide and water
product formed when an acid reacts with a metal
a salt and hydrogen
ethanoic acid
CH3COOH
Alkali
Release OH- ions in aqueous solutions
Soluble in water
Eg NaOH
KOH
Acid + metal
Salt + hydrogen
Acid + metal oxide
Salt + water
Acid + metal hydroxide
Salt + water
Acid + metal carbonate
Salt + water + carbon dioxide
Neutralisation
Acid + metal
Acid + metal oxide
Acid + metal hydroxide
Redox
Acid + metal carbonate
Salt
Any chemical compound formed from an acid when a H+ ion from the acid has been replaced by a metal ion or another positive ion
E.g. ammonium ion, NH4+
Hydrated
Crystalline compounds contain water molecules
Anhydrous
Substances that contain no water molecules
H3O
Hydronium ion
Acids and bases with water
Form a reversible reaction
Polyprotic acids
Acids that can donate more than one proton
Weak base info
NH3
Backwards reaction favoured so not many OH ions produced
NH3 + H2O = NH4 + OH
Strong base info
Ex NaOH, KOH
Forward reaction favoured strongly. Lots of OH ions produced
NaOH = Na + OH
Strong acid info
Ex HCl, H2SO4, HNO3
Forwards reaction favoured strongly. Lots of H+ produced
HCl = H+ + Cl-
Ammonia exemption
Ammonia doesn’t produce OH ions directly
It reacts with water first and accepts a proton to produce ammonium ions and OH ions
Salts are made from
Metal and non-metal
Ammonia + acids
Ammonium salts but no water
2NH3 + H2SO4 > (NH4)2SO4
Triprotic
1 mole of H3PO4 will produce 3 moles of H+ ions
Diprotic
1 mole of H2SO4 will produce 2 moles of H+ ions
Monoprotic
Eg nitric acid
1 mole of HNO3 will produce 1 mole of H+ ions
Weak acid example + info
CH3COOH (ethanoic acid) and other carboxylic acids
Backwards reaction favoured so not many H+ produced
CH3COOH = CH3COO + H+
Making standard solutions
Weigh the sample bottle containing the required mass of the solid on a 2dp balance
Transfer to beaker & rinse to transfer all of solid
Add 100cm3 of distilled water to beaker. Use a glass rod to stir to dissolve the solid
Pour solution into 250cm3 graduated flask via a funnel
Rinse beaker and funnel and add washings from the beaker and glass rod to the volumetric flask
Make up to the mark with distilled water, using a dropping pipettes for the last few drops, fill so meniscus sits of the line
Invert several times to ensure uniform solution
Standard solutions
Titrated against the unknown concentration in the conical flask
have a known concentration
Made from solids with a known mass dissolved in water to fixed volume in volumetric flask
Titrations use
To work out the concentration of an acid or alkali
Ions dissociating
When soluble ionic solids dissolve in water, they will dissociate into separate ions
This can lead to the concentration of ions differing from the concentration of the solute
Diluting a solution
Pipettes 25cm3 of original solution into a 250cm3 volumetric flask
Make up to the mark with distilled water using a dropping pipettes for the last few drops
Invert flask several times to ensure uniform solution
New diluted concentration
= original conc x (original vol/new diluted vol)
Safety and hazards
Irritant - dilute acid and alkalis so wear goggles
Corrosive - stronger acids and alkalis wear goggles
Flammable - keep away from naked flames
Toxic - wear gloves, avoid skin contact, wash hands after use
Oxidising - keep away from flammable or easily oxidised materials