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Chemistry Revision- AP2 - Coggle Diagram

- - - - increasing the temperature-particles have more KE-therefore they move faster-more frequent collisions-and rate of reaction increases.
    - - increasing surface area-more area in the same volume of the solid-more frequent collision-so rate of reaction increases.
    - - Increasing concentration-more particles in the same/given volume-more frequent collisions-so increased rate of reaction.
    - - Speeds up the reaction-lowers the activation energy-provides an alternate route
    - - pressure increases-same number of particles occupy a smaller space-more frequent collisions-rate of reaction increases.
  - - - 1) add a set volume of dilute hydrochloric acid to a conical flask, and place it on a mass balance.
        2) add some magnesium ribbon to the acid and block the flask immediately with cotton wool.
        3) start the stopwatch and record the mass on the balance. take readings at regular intervals.
        4) plot results in a table, and work out the mass lost for each reading.
        5) plot a graph of mass lost against time.
        6) repeat with more concentrated solutions.
      - to improve results: repeat the experiment. amount of magnesium ribbon and volume of acid used should be kept the same each time-only each acid's concentration.
    - - 1) add a set volume of sodium thiosulfate to a conical flask. 2) place the flask on a on a piece of paper with a black cross drawn on it. Add dilute HCl to the flask and start the stopwatch.
        3) yellow precipitate of sulfur is formed which would make the solution cloudy, and thus the black cross would disappear. record how log it takes for the cross to disappear.
      - repeat the experiment. concentration of one of the reactants can be changed, but the depth of the liquid must be kept the same each time.
  - - - when the rates of forwards and backwards reaction are equal. At equilibrium, both reactions are still happening but there is no overall effect (dynamic equilibrium). dynamic equilibrium only takes place in a closed system.
    - - temperature changes
        
        all reactions are exothermic in one direction and endothermic in the other direction.
        temperature decreases-equilibrium moves to the exothermic direction, and increases temperature. more products for exothermic and less for endothermic.
        temperature increases-equilibrium shifts to the endothermic direction, and tries to decrease it. more product for endothermic and less for exothermic.
      - pressure changes
        
        increase pressure-equilibrium moves to the side with the fewest moles.
        decrease pressure-equilibrium moves to the side with the most moles.
      - concentration changes
        
        increasing conc of reactants-system decreases it by making more products
        decreasing conc of products-system increases it by making less reactants
    - - If the conditions of a reversible reaction is changed at equilibrium, then the system will respond to counteract the change.
- - - - reaction of Alkenes
        
        Addition reaction: Alkenes react with bromine water, an alkene causes the bromine to change colour from orange to colourless. However, alkanes do not discolourize Bromine water.
        Addition of hydrogen: hydrogen reacts to break the double carbon to carbon bond, and alkene is reacted with hydrogen in the presence of a catalyst.
        
        unsaturated hydrocarbons-they have a double carbon to carbon bond.
        alkenes are more reactive than alkanes. this is because they have a double carbon to carbon bond and these open up to make single carbon to carbon bond, which allows to carbon atoms to bond with other atoms.
      - first 4 alkenes
        
        ethene (C2H4)
        
        propene (C3H6)
        
        butene (C4H8)
        
        Pentene (C5H10)
    - - Alkanes
        
        general formula: CnH2n+2 .saturated compounds-they have a single carbon to carbon bond.
        
        first 4 alkanes are:
        
        methane (Ch4)
        
        ethane (C2H6)
        
        propane (C3H8)
        
        butane (C4H10)
    - - less viscous it is (more runny)
      - more volatile it is (lower boiling points)
      - the more flammable it is
    - - when there is enough oxygen. A lot of energy is released in complete combustion. waste products: CO2 and H2O. Both carbon and hydrogen from the hydrocarbon are oxidized.
    - - When there isn't enough oxygen. Produces carbon monoxide and water. Results in a smoky yellow flame. Less energy is released than complete combustion
  - - - 1) Methanoic acid (HCOOH)
      - 2) Ethanoic acid (CH3COOH)
      - 3) Propanoic acid (C2H53COOH)
      - 4) Butanoic acid (C3H7COOH)
    - - they react with carbonates and produce salt, water, and CO2
      - salts that are formed all end in '-anoate'. Methanoic acid forms methanoate, and ethanoic acid will form ethanoate
      - carboxylic acids dissolve in water, releasing their H+ ions, however they onot fully ionise and therefore they have a higher pH than aqueous solutions of strong acids with the same concentration.
        carboxylic acids form weak acidic solutions.
    - - functional group: '-COO-'
      - The are formed from an alcohol and a carboxylic acid. an acid catalyst is usually used
      - Alcohol + carboxylic acid (forms) ester + water
  - - - polymer chains are created when monomers react together and form bonds between them. every time a new bond is formed, a small molecule is lost.
      - No. of types of monomers
        
        2 monomer types each containing two of the same functional groups. or 1 monomer type with 2 different functional groups.
      - No. of products
        
        2 types of products- polymer and a small molecule
      - functional groups
        
        2 reactive groups on each monomers
    - - No. of types of monomers
        
        only 1 monomer type containing a double Carbon to carbon bond. (C=C)
      - No. of products
        
        1 product formed
      - functional groups involved
        
        C=C bond in monomer
    - - Amino acids
        
        contains 2 different functional groups- NH2 and COOH
        
        proteins are polymers of amino acids. lots of amino acids join to form a protein.
        
        can form polymers such as polypeptides via condensation polymerisation. one or more long chains of polypeptides are known as proteins.
        
        there are 20 different amino acids
      - DNA
        
        large molecule- double helix structure
        
        there are 4 different monomers
        
        nucleotide (monomer) : Phosphate group, sugar, organic base.
      - simple sugars/ carbohydrates
        
        starch and sucrose are monomers
        
        starch- 1 sugar (glucose)
        
        sucrose- 2 diff. sugars.
- - - - Solubility: molecules with a higher solubility in the solvent, and which are less attracted to the paper, will spend more time in the mobile phase-and they'll be carried further up the paper
      - Attraction: the more attracted a substance is to the paper, the less it moves, lower down the paper
      - Stationary phase: Where the molecules can't move. Can be a solid or a thick liquid. In paper chromatography this is the chromatography paper.
      - mobile phase: where the molecules can move. always a liquid or a gas. In paper chromatography the mobile phase is the solvent.
    - - beaker is filled with water just below the pencil line on the paper.
        
        Lid-stops solvent from evaporating.
        
        Base line on the chromatography paper must be drawn in pencil- this prevents it from interfering with the ink samples.
        
        Glass rod is used to hold the paper in place (on top of the beaker)
    - - when the experiment reaches the end-mark the solvent front. This is the distance the solvent has travelled along the paper.
      - Rf value
        
        Distance travelled by spot/ distance travelled by the solvent.
        Rf value would always be between 0-1. if you change the solvent, the Rf value changes too.
  - - - A lit splint is placed in a test tube containing hydrogen, and in the presence of hydrogen a squeaky pop noise would be made
    - - Bubbling carbon dioxide through limewater. In the presence of CO2 the limewater would turn cloudy from being colorless.
    - - A glowing splint is placed in a test tube containing the gas. In the presence of oxygen the glowing splint would relit.
    - - Damp blue litmus paper is dipped into chlorine. In the presence of chlorine, the litmus paper would turn red and then white. (chlorine would bleach the litmus paper).
  - - - 1) take a nicrohne wire and dip it in concentrated HCl
      - 2) pass it through a burning flame to sterilise the wire.
      - 3) Dip it in HCl again to reduce contamination
      - 4) take some of the unknown salt on the wire loop
      - 5) place the wire loop next to the burning flame, to test for the positive ions.
    - - sodium: yellow/orange
      - potassium: lilac
      - lithium: Red
      - calcium: orange-red
      - copper: green flame
    - - results
        
        Fe2+ = Green precipitate
        
        Fe3+ = brown precipitate
        
        Cu2+ = blue precipitate
        
        Ca2+ = white precipitate (insoluble in excess)
        
        Al3+ = white precipitate (soluble in excess)
        
        Mg2+ = white precipitate (insoluble in excess)
  - - - add dilute HCl. Take the gas produced and react it with lime water. if limewater turns cloudy, carbonate is present.
    - - add dilute HCl followed by barium chloride solution. if white ppt is formed, sulfate is present.
    - - add dilute nitric acid followed by silver nitrate.
      - results
        
        chloride: white precipitate
        
        bromide: cream precipitate
        
        iodide: yellow precipitate
  - - - to identify metal ions in a sample
      - to determine the concentration of metal ions in dilute solution.
  - - - mixtures that have been prepared using a specific formula
      - precise amount of different compounds
      - have a particular function
      - e.g., cosmetics, paint, medicine.