Random (Chemistry)

• What is the top part and bottom part called in water treatment during sedimentation??

  Top part is called effluent and the collection at the bottom is sludge
• How to treat water ready for drinking

  
  

  1. Filtration
  2. Big bed of sand and gravel to filter smaller bits
  3. Sterilise it by chlorination or ultraviolet light
• Neutralisation Reactions

  1. metal oxides + acid -----> salt + water
  2. metal hydroxides + acid ----> salt + water
  3. metal carbonates + acid ----> salt + water +carbon dioxide
• Electrolyte: a liquid or gel which contains ions and can be decomposed by electrolysis, e.g. that present in a battery.
• What's the positive electrode called?

  Anode
• What's the negative electrode called?

  Cathode
• What's the purpose of the wire in electrolysis?

  Complete current/transfer electrons
• Stages of molten

  1. Purify
  2. Mix with cryolite
  3. Melt
• What's the purpose of cryolite?

  Lower melting point
• Rules of Electrolysis:

  1. If dissolved in water, hydrogen + hydroxide
  2. Will discharge 1 of the ion
• Rules of Cathode in Electrolysis:


  1. Will always be H+ unless Cu2+ is present
• Rules of Anode in Electrolysis:


  1. Will always be the OH- unless halide is present (F,Cl,Br,I)
• La Chatelier's Principle

  1. Position of equilibrium if you change a condition
• La Chatelier's Principle: Temperature

  Will shift in the direction of if it is endothermic or exothermic.
• La Chatelier's Principle: Pressure

  Will depend on the amount of molecules.
• La Chatelier's Principle: Concentration

  More of the concentration of stubstance
• Corrosion

  Iron + Oxygen + Water ----> Hydrated Iron(III) Oxide
• Test for Corrosion

  1. 3 tubes, one with oil on top, 1 with calcium chloride, with both oxygen and water
• Indicators

  Litmus:

  Acid - Red

  Alkaline - Blue

  Phenolphthalein:

  Acid - Colourless

  Alkaline - Pink

  Methyl Orange:

  Acid - Red

  Alkaline - Yellow
• The pH scale measures how acidic/alkaline something is by measuring the hydrogen ion (H+) concentration in a substance.
• Strong acids are completely ionised in solution while weak acids only partially dissociate into H+ ions and their conjugate base anions.
• Percentage Yield = (actual mass of product / theoretical mass of product) x 100
• Reasons for why all reactants do not become all products.

  1. Reactants may not all react (too slow OR reversible reaction)
  2. Side reactions (Passive i.e O2)
  3. Lose of products during reaction
• NPK Fertilisers (Nitrogen)

  1. Important to plants to make amino acids (proteins)
  2. Nitrogen fertilisers (ammonia)
• NPK Fertilisers (Ammonium Reactions)

  1. Reacts in a series of water + oxygen to make nitric acid
  2. Can also react with acids to make nitric acid
• NPK Fertilisers (Phosphorus)(MAIN)

  1. Can be mined however useless, therefore react with acids to produce soluble salts.
• NPK Fertilisers (Phosphorus)(MAIN)

  1. When reacted with Nitric Acid, forms Phosphorus Acid + Calcium Nitrate
  2. When reacted with Sulfuric Acid, forms Calcium Sulfate + Calcium Phosphate (Single Superphosphate)
  3. Also reacts with Phosphorus Acid, forms Calcium Phosphate (Triple superphosphate
• NPK Fertilisers (Potassium)

  1. Simplest to produce Potassium Chloride + Sulphate
  2. Can be mined and directly used
• Fuel Cells (Electrochemical Cell)

  1. Converts between electrical energy and chemical energy
• Fuel Cell (Electrochemical Cell)

  1. As fuel enters, it is oxidised
  2. This sets up an electric potential difference across cells
• Alkali Metals (Group 1)

  1. Soft
  2. Low density
  3. Low melting points
  4. More reactive (Down)
• Alkali Metals (Group 1)

  1. Alkali Metal + Water ----> Metal Hydroxide + Hydrogen
  2. Alkali Metal + Chlorine ----> Metal Chloride
  3. Alkali Metal + Oxygen ----> Metal Oxides
• Halogens & Noble Gases

  F - Poisonous Yellow Gas

  Cl - Poisonous Green Gas

  Br - Poisonous Liquid

  I - Dark Grey Solid producing Poisonous Purple Gas

  Reactivity decreases as you go down

  BP and MP increase as you go down
• Displacement Halides

  1. Halide Salts are colourless
  2. Bromine Water is Orange
  3. Chlorine Water is Colourless
  4. Iodine Water is Brown
• Combustion

  Hydrocarbon + Oxygen(Plenty) ----> Water + Carbon Dioxide
• Incomplete Combustion

  Hydrocarbon + Oxygen(Insufficient) ----> Carbon Monoxide + Carbon
• Cracking & Alkenes

  1. We use cracking to break long hydrocarbons into shorter and alkenes (more reactive(saturated)because of duo bond)
• Burning Magnesium

  1. Burns with a Bright White Flame
  2. Forms a White Powder of 2MgO
  3. Magnesium Oxide is an Alkaline when in Water
• Burning Hydrogen

  1. Burns easily, produces pale blue flame
  2. Burning hydrogen forms Water Vapour(Neutral)
• Burning Sulfur

  1. Burns with a Pale Blue Flame
  2. Produce Sulfur Dioxide
  3. Sulfur Dioxide is Acidic