C4: Chemical Changes (Strong and weak acids and their reactions! (Strength…
C4: Chemical Changes
Strong and weak acids and their reactions!
Acids produce protons in water! They ionise in aqueous solutions, and produce hydrogen ions!
Acids can be strong or weak!
Strong acids ionise fully in water, whereas don't fully ionise in water, and only a few of them release hydrogen ions.
Factor H+ ion concentration changes by = 10^(-x)
Strength and concentration are DIFFERENT!
Strength = proportion of acid molecules that ionise in water.
Concentration = how much acid in a certain volume.
Metal oxides and hydroxides are bases, so when reacted with an acid they produce salt and water. The salt depends on what metal and acid were combined!
Acids and carbonates produce a salt, water AND carbon dioxide!
Metals and their reactivity!
The reactivity series.
The speed of a reaction is indicated by the rate at which bubbles of hydrogen are given off. The more reactive the metal, the faster reaction!
Metals often have to be separated from their oxides!
Oxidation = gain of oxygen
Reduction = loss of oxygen
Oxidation = loss of electrons
Reduction = gain of electrons
Acids and Bases
The pH scale goes from 0-14.
0-6 are acids, 7 is neutral (pure water), 8-14 are alkalis!
You can measure the pH of a solution!
Use an indicator like universal indicator, which changes colour
in different pH levels!
Or use a pH probe attached to a pH meter which measures the
Electrolysis is splitting up with electricity.
A current passes through an electrolyte. The electrolyte is molten or a dissolved ionic compound.
The ions move towards the electrodes and decompose.
The positive ions move towards the cathode and gain electrons (reduction)
The negative ions move towards the anode and lose electrons (oxidisation)
This creates a flow of charge through the electrolyte!
Metals can be extracted using electrolysis!!
Acids and bases neutralise each other!
Acids form H+ ions in water!
Alkalis form OH- ions in water!
A base is a substance that reacts with an acid to form a salt!