Acids, Bases and salts Flashcards
What is pH
It tells you if the solution is acidic, alkaline or neutral.
Acid
Anything with a pH of less than 7. Goes from yellow to red. Formed by hydrogen ions (H+) when dissolved in water.
Base or alkali
Anything with a pH of greater than 7. Goes from blue to light purple. Alkaline is formed by hydroxide ions (OH-) dissolved in the water.
Indicator
Used to find out the pH of solution. It is a dye that changes color depending on if it is acid or alkaline.
Universal indicator
Is a combination of dyes which gives you a different color at the different pH values.
(aq)
Ions are dissolved in water (aqueous)
(l)
liqid
(g)
gas
(s)
solid
Neutralisation
An acid reacts with a base to form a salt and water.
acid + base = salt + water
Ions H+ + OH- = H2O
Salts
Can be made from metals, metal oxides, metal hydroxides, metal carbonates or ammonia.
acid + metal = slat + hydrogen
acid + metal oxide/ metal hydroxide = salt + water
Reactivity of metals with acids
By monitoring the rate of hydrogen production when they react with an acid.
Name of the salt produced
First part of the name of the slat come from the metal and second part from an acid
What are bases?
All metal oxides and metal hydroxides. Soluble hydroxides are called alkalies.
Uses of slat
Ammonium nitrate used as fertilizer. Contains nitrogen essential for plants.
Precipitation
Used to make insoluble salt. It is done by mixing the appropriate amount of one reactant and another.
Crystallization
Process used to get solid salt crystals from salt solution.
Soluble salt
Can be made by reacting hydrochloric or sulphuric acid with metals, insoluble bases and alkalis
Making a soluble salt from insoluble base
By adding a excess of insoluble base or metal to an acid, the excess base is the filtered out.
Making soluble salt from an alkali
Indicator is used to show when the reaction ends.
Uses of precipitation
Can be used as a way of extracting undesired ions from solution. E.g. lead ions from drinking water or metal ions from sewage water before it is discharged to a river.
Titration
An experiment that shows how much reactant is needed to react completely with a certain volume of another reactant.
Phenolphthalein
Is pink in alkalis but colorless in acids.
Methyl orange
Is yellow in alkalis but red in acids
Why is universal indicator not a suitable to use in a titration?
It changes color gradually. For titration you need indicator that will give you a define color change.
Ammonia dissolves in water to…
produce an alkaline solution. It is used to produce ammonium salts.
Insoluble slat can be made by…
reacting solutions of two soluble slats together.
Precipitate
An insoluble solid formed by a reaction taking place in solution.
