Acids, Bases + Salts Flashcards
Reacting acids with metals
Metals above hydrogen (has to be more reactive to displace the hydrogen) in the Reactivity Series react with dilute acids to produce salts and hydrogen gas. The more reactive the metal, the more rigorous the reaction
Acid + Metal –> Salt + Hydrogen
Reacting acids with alkalis and bases
Metal hydroxides and oxides react with acids to produce a salt and water. Soluble bases are called alkalis. This is known as a neutralisation reaction.
Acid + Alkali/Base –> Salt + Water
Reacting acids with carbonates
Carbonates react with acids to produce carbon dioxide, a salt and water
Acid + Carbonate –> Salt + Carbon Dioxide + Water
Naming salts
When naming a salt, the first part of the name comes from the metal ion present. The second part comes from the parent acid.
Parent acids --> salts Hydrochloric Sulphuric Nitric Phosphoric
Chlorides
Sulphates
Nitrates
Phosphates
Solubility rules Nitrates Sulphates Chlorides Hydroxides Carbonates
Nitrates - all nitrates are soluble
Sulphates - all sulphates are soluble except lead and barium
Chlorides - all chlorides (and other halides) are soluble except lead and silver
Hydroxides - all hydroxides are insoluble except potassium, sodium and ammonium
Carbonates - all carbonates are insoluble except potassium, sodium and ammonium
Insoluble hydrochloric compounds
Lead chloride
Silver chloride
Insoluble sulphuric compounds
Barium sulphate
Lead sulphate
Calcium sulphate is only slightly soluble
Insoluble carbonic compounds
Potassium carbonate
Sodium carbonate
Ammonia carbonate
Insoluble hydroxide compounds
Potassium hydroxide
Sodium hydroxide
Ammonia hyrdoxide
State symbol and when to use a solid
S
Insoluble salts
State symbol and when to use liquid
L
Usually water
State symbol and when to use gas
H
H2 CO2 O2
State symbol and when to use aqueous (dissolved in water)
Aq
When starting with an aqueous solution (acids, alkalis), if a soluble salt is produced, it will be dissolved in water
How to write a chemical equation
1) write a word equation (or if confident go straight to symbol equation)
2) write the symbol equation using the rules for writing formulae
3) balance your symbol equation
4) consider the state of each substance and put it after the formula in brackets
Formulae for acids: Hydrochloric Sulphuric Phosphoric Nitric
H = HCl S = H2SO4 P = H3PO4 N = HNO3
Remember:
- acids and alkalis (soluble metal oxides/hydroxides) are …
- if a soluble salt is produced it will be …
- if an insoluble salt is produced it will be …
- carbonates, bases and metals are …
- oxides are always …
Aqueous Aqueous Solid Solids Solid
Why are acid base/alkali reactions called neutralisation reactions?
When oxide ions combine with hydrogen ions water is made. The presence of hydrogen ions is what makes acid, acidic, removing the hydrogen ions, the acid has been neutralised (mix of high and low phs)
Define an acid
An acid is a proton (hydrogen ion) donor
What do acids contain to make them acidic
Hydrogen ions
Define a base
A base is a proton (hydrogen ion) accepter
What do bases/alkalis contain to make them alkali
Hydroxide ions
Equation to show the production of water when an acid and base react
H+ (aq) + OH- (aq) –> H2O (l)
More OH =
More H =
Alkaline
Acidic
Ionic charges for group 1,2,3,(5),6,7
+1,+2,+3,-3,-2,-1
Ionic charges for ammonium, nitrate, hydroxide, hydrogencarbonate, carbonate, sulphate
NH4 +, NO3 -, OH -, HCO3 -, CO3 2-, SO4 2-
what happens when a magnesium ribbon is put into sulphuric/hydrochloric acid
fizzes, magnesium dissolves, exothermic reaction
what happens when a magnesium ribbon is put into sulphuric/hydrochloric acid, test tube held over to collect gas, then a lighted splint put near the top of the tube
hydrogen is present thus makes a squeaky load pop, however sulphuric acid produces more hydrogen
what happens when copper turnings are put into a tube of sulphuric acid
nothing as its below hydrogen in the reactivity series
investigate the reaction of copper oxide with sulphuric acid
- copper oxide reacts with the acid and buzzes turning blue, once more has been added and all reacted with the acid, it goes black and stays black
- it is then filtered to remove copper oxide residue
- the filtrate is copper sulphate and water
- the residue is excess copper oxide
investigate the reaction of calcium carbonate with sulphuric acid
- the mixture fizzes and bubbles up, becoming cloudy, this then slows down and becomes clear again
- this reaction stops occurring when the acid becomes saturated
- the filtrate is calcium chloride and water
- the residue is excess calcium carbonate
- when left to dry the water will evaporate and form crystals of calcium chloride
blue litmus paper turns
red when an acid is present
red litmus paper turns
blue when a base is present
methyl orange indicator turns
- yellow when an alkaline is present
- orange when the substance is neutral
- red when an acid is present
phenolphthalein indicator turns
- pink when a base is present
- colourless when an acid is present
method for making soluble salts
1) Add an excess of the solid reactant to the acid
2) Filter the mixture
3) Heat the mixture until it’s warm
4) Leave in a cool dry place
why not heat a mixture for making soluble salts until its dry
heating for dryness would produce an anhydrous salt
when does the acid need to be heated when making soluble salts
if using any solid except magnesium/carbonate
method for making sodium, potassium and ammonium salts
1) Add a measured volume of alkaline solution to a flask using a pipette (or measuring cylinder)
2) Add a named indicator
3) Add acid from a burette
4) Until a correctly stated colour change
5) Note the volume of acid added
6) Mix the same volumes of acid and alkaline solution without the indicator
what is an insoluble salt
Need to mix together solution of soluble salts, the dissolved ions meet in solution to form a precipitate of the insoluble salt. The other ions are classes as spectator ions.
How to write an ionic equation
1) Write out the word equation
2) Write out the symbol equation with state symbols and balancing
3) Identify ions that make insoluble salt, remove spectator ions from this
4) Write out ionic equation with state symbols, balancing and charges
why can’t we use an indicator to measure in an insoluble salt experiment
salts are neutral from the start to the end
method for making insoluble salts
1) Insoluble salts can be made by mixing together two soluble salts
2) When a soluble salt dissolves, the ions separate from each other and move about between the water molecules
3) When two ions meet in the solution, they will just move apart again, unless in doing so, they are forming an insoluble salt. In this case they stay bonded and come out of solution as a precipitate
4) Salts are made up of a cation/positive ion ( a metal ion or the ammonium ion) and an anion/negative ion ( a non-metal ion)
5) To make an insoluble salt you need to choose two soluble salts that contain the desired positive and negative ions to form your insoluble salt
6) Remember that all nitrates are soluble and all potassium, ammonium and sodium salts are soluble
