Diff Types of Chem Reaction P3 Flashcards
What is the chemical formula for rust?
Fe2O3.xH2O
Which element is required for rusting to occur?
Oxygen
Which compound is required for rusting to occur?
Water
In the rusting experiment what does the deliquescent material calcium chloride do?
It absorbs moisture
Name 5 methods of preventing rusting
- Paint
- Oil or grease
- galvanise
- Sacrificial protection
- alloy stainless steel
What is galvanising?
Coating the iron in a layer of zinc, the zinc will react with oxygen and save the steel
What is sacrificial protection?
A more reactive metal e.g. Magnesium is bolted to the surface of iron and it will react before the iron
Give three features of an oxidation reaction
- Gain oxygen
- Loss of hydrogen
- Loss of electrons
Give three features of a reduction reaction
- Loss of oxygen
- Gain of hydrogen
- Gain of electrons
What would be observed when magnesium burns in air?
Bright white light
White ash
Give a balanced symbol equation for magnesium burning in air.
2Mg + O2 –> 2MgO
Give an ionic equation to show the movement of electrons when magnesium burns in air
Mg - 2e- –> Mg2+
What is observed when copper oxide is reacted with hydrogen?
Black copper oxide turns to copper colour
Give a balanced symbol equation for copper oxide reacting with hydrogen.
CuO + H2 –> Cu + H2O
What is the chemical name for rust?
hydrated iron (III) oxide
In the reaction
Copper oxide + hydrogen –> copper + water
Identify the reducing agent
Hydrogen
Why is the excess hydrogen burnt during the experiment?
Hydrogen is explosive and it is burned to prevent it from escaping into the lab.
Explain why extraction of iron in the blast furnace is a redox reaction.
Fe2O3 + 3CO —> 2Fe + 3CO2
Iron ore (haematite) has lost oxygen = reduction Carbon monoxide has gained oxygen = oxidised Iron has gained electrons Fe3+ + 3e --> Fe = reduction Reduction and oxidation in the same reaction = REDOX
During electrolysis extraction of aluminium from aluminium oxide (bauxite). Explain why this is a redox reaction.
Aluminium oxide loses oxygen = reduction
Aluminium ion gains electrons Al3+ + 3e –> Al = reduction
Oxide ion loses electrons 202- -4e –> O2 = oxidation
In the Haber process, explain why it is a redox reaction
N2 + 3H2 –> 2NH3
Nitrogen gains hydrogen = reduction
What is observed when sulfur burns in air?
A blue flame
Yellow solid sulfur melts
Pungent smell
