C5- Chemical Changes Flashcards
What is the reactivity series?
A list of metals in order of their reactivity with the most reactive metals at the top and the least reactive ones at the bottom
Order of reactivity
Potassium, sodium, Lithium, Calcium, magnesium, aluminium, Zinc, Iron, Tin, lead, copper, Silver, Gold
Potassium, Sodium, Lithium, Calcium reaction with water
Fizz, giving off hydrogen gas, leaving an alkaline solution of metal hydroxide
Magnesium, Aluminium, Zinc, Iron reaction with water
Very slow reaction
Tin and lead reaction with water
Slight reaction with steam
Copper, Silver, Gold reaction with water
No reaction
Potassium, sodium, lithium reaction with dilute acid
Explode
Calcium, magnesium, aluminium, zinc, iron reaction with dilute acid
Fizz, giving off hydrogen gas and forming a salt
Tin and lead reaction with dilute acid
React slowly with warm acid
Copper, silver, gold reaction with dilute acid
No reaction
Reactivity of metals and displacement
A more reactive metal will displace a less reactive metal from an aqueous solution of one of its salts
Magnesium + copper sulfate ~>
Magnesium sulfate + copper
This is a displacement reaction which happens because Magnesium is more reactive than copper
Where do non metals carbon and hydrogen fit in the reactivity series?
Carbon is between aluminium and zinc
Hydrogen is between lead snd copper
What needs to happen to most metals in the Earth’s crust in order for them to be used?
The metals need to be chemically separated from other elements
Whether it is worth extracting a metal depends on…
How easy it is to extract from its ore
How much metal the ore contains
The changing demands for a particular metal
What is chemical reduction?
The removal of oxygen from a compound
Metal + acid ~>
Salt + hydrogen
Salts formed when you react metals with different acids
Hydrochloric acid forms chlorides
Sulfuric acid forms sulfates
Nitruc acid forms nitrates
What is a redox reaction ?
A reaction where reduction (gain of electrons) and oxidation (loss of electrons) both occur
Acid + base
Salt + water
Ions of group 1 metals
+1
Ions of group 2 metals
+2
Aluminium ion
+3
Ammonium ion
+1 e.g NH4^+
Transition metals ions (dependent on roman numeral)
E.g Copper (II) ion = +2
Ions of group 7 non metals
-1
Nitrate ions
-1
Sulfate ions
-2
Making salts practical (basic steps)
- Add copper oxide in excess to sulfuric acid. Warm gently on a tripod and gauze
- When the reaction is complete filter the solution to remove excess copper oxide.
- Evaporate half the water from the solution using a water bath. Leave the solution to form crystals in a warm room for a day.
- Pat dry if any solution remains on the crystals
Acid + alkali
Salt + water
Acid + carbonate
Salt + water + carbon dioxide
What are alkalis?
Soluble hydroxides. An example is sodium hydroxide solution
What are bases?
Substances that can neutralise acids
What can you use to find the PH of a solution?
Universal indicator
pH scale
0 - most acidic
7 - neutral
14 - most alkaline
Where is pure water on the pH scale ?
pH 7
What do strong acids do in solution?
Ionise completely
What do weak acids do in solution?
Do not fully ionise in solution
Examples of strong acids
Hydrochloric acid
Nitric acid
Sulfuric acid
Examples of weak acids
Ethanoic acid
Citric acid
Carbonic acid
Concentration of Hydrogen ions (H+) in relation to pH values
As the concentration decreases by a factor of 10 the pH value increases by one unit
e.g
0.10 to 0.010
1 to 2 on pH scale
