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Types of chemical reactions - Coggle Diagram
Types of chemical reactions
Acid and Bases
Neutralisation is when a reaction occurs with acid that gives water as well as a salt
Used to reduce acidity in soil using slaked lime ( CaOH ) and calcium carbonate ( CaCO3), and neutralisation takes place
Equation for neutralisation : HCl + NaOH --> NaCl + H2O, with Cl being the non-metal and sodium being the metal to produce the salt.
Acid reactions
acid+metal --> salt+hydrogen
acid + base --> salt+water
acid + metal carbonate --> salt + water + carbon dioxide
Base reactions
Bases react with acids
Bases like sodium, potassium and calcium hydroxide react with ammonia salts to produce ammonia gas
pH and indicators
determines extent of a chemical reaction
weak acids that determine concentration of H+ via color change
Examples : Methyl orange, Methyl red, Phenolphthalein
formation of salts
able to form salts by reacting acid with metals, insoluble bases, or soluble base, and carbonates
Method : Add salt to dilute acid to dissolve it when warming, and solution changes color. Add until no more will dissolve. Remove solid by filter, and heat solution to form crystals.
Making insoluble salts through precipitation
Ex : Barium sulfate ( insoluble salt ) mix barium chloride and magnesium sulfate.
Process : Mix solutions, forms precipitate. Filter precipitate and rinse with distilled water. Place in warm oven to dry.
Uses of precipitation
Coloured pigments for paint
cleaning up waste water
Making photography film
Redox reactions
Reaction goes either direction. either forward or backward reaction
Endothermic or exothermic in the other. Same amount of energy transferred each time
Ex : Blue crystals are heated to turn into white powder. The reaction is easily reversible by adding water. the anhydrous copper(II) sulfate gets hot and turns back to blue
Oxidaition :lose electron, increase oxidation state, gain oxygen
Reactivity series
predicts chemical reactivity of an element
Electrochemical cells
Electrolysis
Electrode
The electrodes are anodes and cathodes that are attached respectively each to the negative and positive terminal of a cell
the solution gets decomposed, and the ions carry current through liquid and electrons carry the current through wire.
At the cathode ( - ) , metal or hydrogen forms, and anode ( + ), a non-metal except hydrogen forms.
Extraction of metals
Iron
Iron is extracted through a blast furnace.
Reactions in the blast furnace
Stage 1 : combustion, redox reaciton. Reaction is exothermic to heat the furnace
Stage 2 : Endothermic to take in heat from the furnace
Stage 3 : Redox Reaction ( Iron(III) oxide + carbon monoxide --> iron + carbon dioxide )
Charge containing iron ore, limestone and coke is added in the top of the furnace
Aluminium
Extracted through electrolysis
Alumina melts at high temperature, so it is dissolved in molten cryolite.
At the cathode, aluminium gains electrons and drops to the bottom as a molten metal
At the anode, oxygen loses electrons and reacts with anode to eat carbon. Needs to be replaced while alumina is broken down. ( 2Al2O3 --> 4Al + 3O2 )
Zinc
For Zinc blende. Mainly zinc sulfide. It is obtained by roasting in the air giving zinc oxide and sulfur dioxide
Using carbon monoxide, where it is in a furnace ( ZnO + CO --> Zn + Co2 )
Corrosion
Corrosion of iron and steel is called rusting
Objects like a car gets corroded by being broken down by reaction with something in the atmosphere
Prevent rusting by ensuring oxygen and water do not react with the metal
When rusting occurs, iron becomes oxidised, since magnesium is more reactive, it loses electrons more easily. Magnesium dissolves to protect iron.
