C2.6 Acids, bases and salts Flashcards
What does the state symbol (s) mean?
Solid
What does the state symbol (l) mean?
Liquid
What does the state symbol (g) mean?
Gas
What does the state symbol (aq) mean?
Aqueous- dissolved in water
What is an acid?
A substance with a pH less than 7
What do acids form in water?
H+ ions
What is a base?
A substance with a pH greater than 7
What is an alkali?
A base that dissolves in water
What do alkalis form in water?
OH- ions
H+ ions make a solution…
Acidic
OH- ions make a solution…
Alkaline
Acid + Base =
Salt + Water
What is the reaction between acids and bases called?
Neutralisation
Metals react with acids to give…
Salts
Acid + Metal =
Salt + Hydrogen
What will hydrochloric acids always form?
Chloride salts
What will sulfuric acid always form?
Sulfate salts
The more reactive the metal reacted with the acid…
The faster it will go
Which metal doesn’t react with acids to form salts?
Ones less reactive than hydrogen e.g. copper
What are metal oxides metal hydroxides?
Bases
Acid + Metal Oxide =
Salt + Water
Acid + Metal Hydroxide =
Salt + Water
What decides the salt?
The combination of the metal and acid
e.g. Hydrochloric acid + copper oxide ==> copper chloride + water
Hydrochloric acid + sodium hydroxide ==> sodium chloride + water
Nitric acid produces…
Nitrate salts when neutralised with alkalis (but with metals it forms oxides)
What does ammonia and nitric acid make?
Ammonium nitrate
What can ammonium nitrate be used for?
Making fertiliser, it can neutralise soil and contains nitrogen which plants need to make proteins
How do you make a salt using a metal or insoluble base?
Crystalisation
How do you make a salt using an alkali?
Add the right amount of alkali to neutralise the acid then when it is finished use crystalisation
How do you make an insoluble salt?
Precipitation reaction
What is crystallisation?
You mix the two reactants and wait till they have reacted. Once they have reacted you filter out the excess solids leaving just the desired solution. You then heat the solution partly to evaporate the water, then you leave the water to evaporate naturally and slowly. You will be left with crystals
What is a precipitation reaction?
Mix the two solutions. Once the salt has precipitated out an dis lying at the bottom of the flask you filter it out from the solution, wash it and dry it
Soluble hydroxides are…
Alkalis
What can precipitation be used for?
Removing unwanted ions from solutions e.g. treating dri
What is the pH scale?
The measure of the acidity or alkalinity of a solution
H2+ (aq) + OH- (aq) =====>
H2O (l)
