Chemical Analysis

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  • Chemical Analysis and (Gases, reversible reactions and Ammonia
    • Chemical Analysis
      • Qualitative
        • Uses:- Blood tests and water tests
        • Each result must be different so that you have a definite result
        • Testing for ions
          • Flame test
            • Dip clean wire in compound then put above flame
            • Calcium = brick-red flame
              • Sodium = yellow/orange flame
                • Flame test
                  • Dip clean wire in compound then put above flame
                  • Calcium = brick-red flame
                    • Sodium = yellow/orange flame
                      • Potassium = lilac flame
                        • Copper = blue-green flame
                        • Copper = blue-green flame
                      • Potassium = lilac flame
                • Positive ions test (precipitate)
                  • Add few drops of sodium hydroxide (NaOH) to the compound solution
                  • Hydroxide reacts with metal and turns them into an insoluble metal hydroxide
                  • Results:
                    • Calcium = white
                    • Copper = blue
                    • Iron 2 = green
                    • Iron 3 = brown
                    • Aluminium =  White but then redissolves
                    • Ammonium = No precipitate but gives off ammonia
            • Quantitative Analysis
              • Measuring amounts
                • THE MOLE
                  • Molar mass = mass of one mole
                  • Mass in g = no. moles x Mr
                  • No. moles = mass in g/ Mr
                • Solutions and concentrations
                  • Find out how much substance is dissolved by evaporating the solution
              • Hard Water
                • Forms soap scum = wasted water
                • Caused by calcium and magnesium ions
                  • Obtained by water flowing over rocks
                • 2 types :
                  • Temporary
                    • Caused by calcium carbonate (chalk)
                • Removed by Boiling
                  • Temporary
                    • Caused by calcium carbonate (chalk)
                • Removed by an ion exchange column (swaps ions with sodium ions)
                  • Permenant
                    • 2 types :
                      • Caused by calcium sulfate
                • Titrations
                  • Used to find out concentrations
                    • Neutralization reaction to show how much acid is needed to neutralize an alkali (or vice versa)
                  • Instructions
                    • 1. Use pipette filler to add alkali  to a conical flask with drops of indicator
                      • 2. Fill a burette with acid
                        • 3. Add the acid to the alkali slowly and swirl the flask every now and again
                          • 4. The indicator will become colourless when all of the alkali has been neautralized
                            • 1. Use pipette filler to add alkali  to a conical flask with drops of indicator
                              • 2. Fill a burette with acid
                                • 3. Add the acid to the alkali slowly and swirl the flask every now and again
                                  • 4. The indicator will become colourless when all of the alkali has been neautralized
                  • Preparing soluble salts
                    • Made using an acid and insoluble reactant
                      • Add base to acid
                        • Filter out excess solid
                          • Evaporate the water and crystalise the salt
                    • Made using an acid and soluble reactant
                      • Reacting acid and alkali
                        • Titratiion needs to be performed to know how much to add
              • Gases, Reversible reactions and ammonia
                • The Haber Process (Reversible reaction)
                  • Nitrogen and hydrogen are needed to make ammonia
                    • Nitrogen extracted from air (78% nitrogen)
                    • Hydrogen obtained from natural gases
                    • Creates dynamic equilibrium as not all oxygen and hydrogen is changed into ammonia
                  • Conditions used:
                    • High pressure to increase percentage yield of ammonia without increasing expenses to much
                    • High temperature to increase the rate of reaction as there is a higher yield in a shorter length of time
                    • Iron catalyst is used
                    • Ammonia is collected as a gas but cools to liquid in the condenser
                      • Ammonia is used to make nitrogenous fertilisers
                        • Increase plant growth
            • Halide test
              • Testing for ions
                • Positive ions test (precipitate)
                  • Add few drops of sodium hydroxide (NaOH) to the compound solution
                  • Hydroxide reacts with metal and turns them into an insoluble metal hydroxide
                  • Results:
                    • Calcium = white
                    • Copper = blue
                    • Iron 2 = green
                    • Iron 3 = brown
                    • Aluminium =  White but then redissolves
                    • Ammonium = No precipitate but gives off ammonia
              • Add nitric acid(HNO3) then silver nitrate(AgNO3)
                • Acid gets rid of carbonates
              • Results:
                • Chloride = white precipitate
                  • Bromide = cream precipitate
                    • Iodide = Yellow
                • Bromide = cream precipitate
                  • Iodide = Yellow
            • 6.023 x 10(power of 23)
              • THE MOLE
                • Molar mass = mass of one mole
                • Mass in g = no. moles x Mr
                • No. moles = mass in g/ Mr
              • No. of particles (compound or element) with the same no. grams as the relative mass
            • Concentration =  Mass/ volume
              • Solutions and concentrations
                • Find out how much substance is dissolved by evaporating the solution
              • Measured in g/dm(3)-mass concentration or mol/dm(3)- mole concentration
              • Mole concentration = mass-concentration /  Mr
              • Mass concentration = mole-concentration x Mr
            • Calculating volumes
              • Gases, Reversible reactions and ammonia
                • The Haber Process (Reversible reaction)
                  • Nitrogen and hydrogen are needed to make ammonia
                    • Nitrogen extracted from air (78% nitrogen)
                    • Hydrogen obtained from natural gases
                    • Creates dynamic equilibrium as not all oxygen and hydrogen is changed into ammonia
                  • Conditions used:
                    • High pressure to increase percentage yield of ammonia without increasing expenses to much
                    • High temperature to increase the rate of reaction as there is a higher yield in a shorter length of time
                    • Iron catalyst is used
                    • Ammonia is collected as a gas but cools to liquid in the condenser
                      • Ammonia is used to make nitrogenous fertilisers
                        • Increase plant growth
              • Avogadro's law - One mole of any gas occupies 24dm(3)
              • Volume of gas (dm) =Mass of gas/Mr of gas X 24
              • You can calculate volumes in reactions
            • Reversible reactions
              • Where the products of a reaction can react with each other to turn back tot eh original reactants
              • Reversible reactions will reach dynamic equilibrium
                • Closed system -  no products or reactants can escape
              • Position of equilibrium is dependent on the temperature and pressure
                • Raise pressure = increase the reaction with less volume
                • Lower pressure = increase reaction with more volume
                  • Raise pressure = increase the reaction with less volume
                  • Catalysts do not alter the position of equilibrium but speed up the reaction
                    • Lower temp = exothermic reaction increase
                      • Position of equilibrium is dependent on the temperature and pressure
                        • Lower pressure = increase reaction with more volume
                          • Catalysts do not alter the position of equilibrium but speed up the reaction
                            • Lower temp = exothermic reaction increase
                              • Raise temp =endothermic reaction increase
                        • Raise temp =endothermic reaction increase
                • Both reactions are still happening but are equal
                  • Reversible reactions will reach dynamic equilibrium
                    • Closed system -  no products or reactants can escape
                • Entering rivers can cause eutriphication

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