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AS and A Level: Inorganic Chemistry
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Top tips for writing reactions
- 1 Remember to balance the charges on any ionic compounds. The common ions are NO3-, SO42-, OH- and CO32-.
- 2 Do not forget to put state symbols on all of your balanced reactions.
- 3 Each side of the reaction must have the same number of atoms on it. Think about a balanced seesaw.
- 4 Your three main acids that you will use have the formulae HNO3 (nitric acid), H2SO4 (sulphuric acid) and HCl (hydrochloric acid).
- 5 Remember that all metal hydroxides and metal oxides are bases. This will help you when using word equations to figure out your products.
Five common mistakes students make when studying inorganic chemistry
- 1 When observing a gas being produced, you would not write “I saw a gas” as most gases are invisible. Instead you should write “I saw bubbling / fizzing / effervescence”.
- 2 When asked to write a word equation, students often write a symbol equation and vice versa. This will get you no marks in the exam.
- 3 - When asked for “standard conditions” people often say “room temperature”. This is not sufficient. You must say 25 degrees celsius (298K). Other standard conditions you must know are 1 atmosphere of pressure and concentrations of 1 mol dm-.
- 4 If you are asked to state a colour change you must state the initial and final colour.
- 5 Students often give group 2 metals a 1+ charge. Remember that all group two metals (Be, Mg, Ca, St, Ba, Ra) have a 2+ charge.
Five word equations that you must know
- 1 Acid + base / alkali = salt + water (eg HCl + NaOH becomes NaCl + H2O)
- 2 Metal carbonate = metal oxide + carbon dioxide (eg CaCO3 becomes CaO + CO2)
- 3 Metal + oxygen = metal oxide (2Mg + O2 becomes 2MgO)
- 4 Metal + water = metal hydroxide + hydrogen (eg 2Na + 2H2O becomes 2NaOH + H2)
- 5 Metal oxide + water = metal hydroxide (eg CaO + H2O becomes Ca(OH)2)
- Marked by Teachers essays 2
- Peer Reviewed essays 9
Its like going into an empty closet with someone relative to going into an empty auditorium with someone. The chances of interaction within the closet are greater than the chances within the auditorium. So less energy required to move around to increase the chances of bumping into one another. What is the Active Site? The active site of an enzyme is the binding site where catalysis occurs. The structure and chemical properties of the active site allow the recognition and binding of the substrate.
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ammonia Water of crystallisation -Water of crystallisation refers to water molecules that form an essential part of the crystalline structure of a compound. Often the compound cannot be crystallised if water molecules are not present. -The empirical formula of a hydrated compound is written in a unique way: -The empirical formula of the compound is separated from the water of crystallisation by a dot. - The relative number of water molecules of crystallisation is shown after a dot. Oxidation number: in a chemical formula each atom has an oxidation number.
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1 2 3 End Burette vol (ml) 46.70 43.95 43.70 Start Burette vol (ml) 06.50 01.65 01.30 Amount used (ml) 40.20 42.30 42.40 Using the two best titres (within 0.1 ml), on average 25.0cm3 of LiOH required 42.35cm3 of 0.1 mol dm-3 HCl to titrate. Calculate the number of moles of HCl used: LiOH(aq) + HCl(aq) --> LiCl(aq) + H2O(l) - 42.30 + 42.40 / 2 = 42.35cm3 - Average titre = 42.35 cm3 - 42.35cm3 = 0.04235 dm3 We are using HCl of 0.1 mol dm-3 and hence No.
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Therefore, this concentration of acid has not got any risk. However, we will still be taking precautions in order to avoid any possible harm. We will use goggles to avoid acid contact with the eyes and gloves to avoid direct contact with the hands when using it. Also, if the acid is spilt on skin or clothes we will rinse it with water and then wipe it using a dry cloth.4 If it spills either on the floor or on the table, we will clean it up using a damp cloth with water.
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I can read the burette to the nearest 0.05cm3 so the precision error is �0.025cm3 for each reading. I will have to read the burette at the beginning and end of the titre so the precision error for each titre is �0.05cm3. If the titre is 30cm3 the error is (0.05/30.00) x 100 = 0.16% which is acceptably low. A pipette 7 I will need a very accurate, glass pipette which I can use to transfer a specific known volume of sulfuric acid added to the conical flask to be reacted.
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Formula of Magnesium Oxide = Mg O Comparison between calculated empirical formula and literature empirical formula and Sources of Error: The literature empirical formula for Magnesium oxide is MgO meaning the ratio between Magnesium and Oxygen is 1:1. However the results from my experiment differed greatly. Our results ended up in a ratio of 13:3. This could be a result of numerous sources of error and the limitations of the method. There were several opportunities for sources of error, some of which include the fact that we did no repeats.
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4.> Add about 10cm3 of 2M H2SO4 to the mixture and then few drops of starch solution as indicator. Quickly, titrate the mixture with 0.0057M iodine solution. 5.> Record the titre required to produce pale blue colour. 6.> Repeat steps 2-5 for 2-3 times. Data Analysis Trial 1st 2nd Final reading /cm3 3.05 12.80 26.30 Initial reading /cm3 0.25 9.70 23.25 Volume of I2 added /cm3 2.80 3.10 3.05 Average volume of I2 added /cm3 3.075 Concentration of I2 solution: 0.0057 M Volume of wine bottle: 750 cm3 Number of moles of 0.0057M I2 in the titre: (3.075)(0.0057) = 0.01753 mmol Number of moles of SO2 in the 25cm3 sample: 0.01753 mmol Number of moles of SO2 in the bottle of wine: 0.01753 x 30 = 0.5259 mmol Mass of SO2 in the bottle of wine: (0.5259)(32+16x2)
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To calculate the average titre I will use the following method: Average Titre = (24.20 + 25.25) 2 = 24.225 cm3 In this titration there are two half equations that are involved, the first is when the copper (II) sulphate is added to the potassium iodide: 2Cu2+ + 4I- --> 2CuI + I2 The second half equation takes place when the sodium thiosulphate is titrated into the solution containing the Cu2+ and iodine: I2 + 2S2O32- --> S4O62- + 2I- As I need to find the concentration of the Cu2+ I have to look at both half equations to find the ratio of Cu2+ to S2O32-, which is 1:1.
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The separating funnel was allowed to stand near the window for 20 minutes. 6. A distillation apparatus was set up, as in the diagram below. 7. The small flask in the above set-up was weighed. 8. The lower aqueous layer in the separating funnel was discarded into a beaker. 9. Excess sodium hydrogencarbonate was added 2ml at a time into the separating funnel until no more gas was produced. 10. The lower aqueous layer was once again separated. 11.
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This will occupy 30dm3 in total. One mole of copper carbonate has a mass of 123.664g. Because most gas syringes are 100cm3 the amount of gas evolved needs to be less than this. To make the experiment such that 60cm3 will be evolved the mass of copper carbonate needs to be divided by 500. Having 60cm3 gas evolved will leave room in the gas syringe in case the conditions are not perfect for the experiment. If the volume was calculated so that 90cm3 gas would be evolved there is a chance that the gas syringe would not be able to take it.
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Chemistry notes - Chemistry of Natural Resources, Elements from the Sea, Ions in Solids and Solutions
This creates one mole of positively charged ions. Across Periods As you travel across the period on the periodic table, the energy required to remove an electron increases. This is because as you move across the period, more electrons are added to the same shell. This results in a greater attraction between the nucleus and the electron, so more energy is needed to remove the electron. Across Groups As you travel down the groups on the periodic table, the energy required to remove an electron decreases.
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Titration of standard K2Cr2O7 with FAS Trial 1 2 3 Initial volume of FAS (ml) 3.30 13.30 23.30 Final volume of FAS(ml) 13.30 23.30 33.30 Volume of FAS used(ml) 10.00 10.00 10.00 Average volume of FAS solution used = (10.00+10.00+10.00) / 3 = 10.00 ml 2) For the blank solution, 25.20ml of FAS was used to titrated it to reach the end-point. 3) Titration of excess K2Cr2O7 in the sample with FAS Initial Volume of FAS (ml) = 0.00 Final Volume of FAS (ml)
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As its density decreases it becomes lighter and these atoms will rise if they happen to be liquid or gas molecules. As the hot molecules rise they are replaced by cold molecules which are heavier. This results in a convection current forming and heat is thus transferred. 2. Conduction: Again as a material is heated the individual atoms gain energy and vibrate faster. They collide with atoms next to them and impart energy to the neighboring atoms and these gain more energy and become hotter.
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Aim: To determine the activation energy of the reaction between bromide ion and bromate(V) ion in acid solution.
Apparatus: Quantity Beaker 1 Boiling tube 2 Stop watch 1 -10o-110oC thermometer 1 Burette 3 V. Procedure: 1. Place 10.00 cm3 of 0.01 M phenol solution, 10.00 cm3 solution A and 10 drops of methyl red indicator into a boiling tube. 2. Place 5.00 cm3 of 0.5 M H2SO4 in the second boiling tube. 3. Place both boiling tubes into a large beaker of water which is maintained between 49?C - 51?C by careful warming. Allow the contents of the tubes to reach the temperature of the water bath (?
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This can be done by titrating nickel(II) solution against EDTA with murexide as indicator. Initially the mixture in the conical flask should appears yellowish green due to the domination of the green nickel-water complex over a trace amount of yellow Nickel-murexide complex. When EDTA are gradually added, the solution should start to turn blue due to the increasing concentration of Nickel-EDTA complex. When all the Nickel-murexide complex are finally replaced by Nickel-EDTA complex, a pale blue colour should appear, any further addition of EDTA would cause the solution turns dark blue and then violet, which is due to the formation of the original murexide, and this indicates the end-point of the titration.
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The purpose of this experiment is to study the effect of an oxidizing acid [concentrated sulphuric(VI) acid] and a non-oxidizing acid [ concentrated phosphoric(V) acid] on three solid potassium halides, namely potassium chloride, potassium bromide and pot
solution green Br2 * A red colour is observed when adding hexane I- * Steamy violet fumes are formed * A bad egg smell is detected HI * White fumes are formed with aqueous ammonia H2S * It turns lead(II) ethanoate paper black I2 * A violet colour is observed when adding hexane Table 3 Halide ion Action of conc. H3PO4(l) Product(s) Confirmatory test of product(s) Cl- Steamy fumes are formed on warming HCl White fumes are formed with aqueous ammonia Br- HBr I- HI 4.
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ionic compound made from the neutralisation of a Metal and an Acid Different Metals have different rates of reactions, Metals like Sodium react dangerously Fast Acids like nitric acid have such an oxidation state that makes them react violently with other metals and may cause explosive reactions. Its reaction with a metal does not liberate hydrogen and salt produced usually has a very high oxidised state and heavy corrosion may be the result that is there would be a break down in the properties of the metal reacting with it and nitrogen oxide is produced B)
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One of its current processes of production is by heating one of its compounds 'phosphate', with silica and coke in a furnace. Phosphorus exists in 3 main allotropic forms: white, red and black. Allotropes are forms of an element with different physical and chemical properties. White phosphorus in its pure form, is a transparent waxy solid, however it is sometimes yellow due to traces of red phosphorus impurities that exist within it. White phosphorus is extremely volatile in air and so spontaneously bursts into flames (pyrophoric - it self ignites in air), forming Phosphorus Pentoxide: P4O5 2 , which is the reason for it being stored underwater at room temperature; it's insolubility in water allows this to happen.
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Safety Calcium is reactive with both water and acids. Care should be taken when water is added and eye protection worn at all times. Calcium is highly flammable. Apparatus * Eye protection * Polystyrene cup * 250 cm3 beaker * 100 cm3 measuring cylinder * -50 to 50 �C thermometer * 3 g calcium metal * 8 g of powdered calcium carbonate * 1.0 M HCL (aq)
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Aim; 1)To prepare a standard potassium dichromate solution 2)To standardize the ammonium iron(II) sulphate solution 3)To determine the given unknown potassium permanganate solution 4)To estimate the concentration of hydrogen peroxide
solution Titrant (in burette): Potassium Dichromate Titrate (in conical flask): 25.0cm3 of Fe2+ Solution Indicator used: N-phenylanthranilic acid indicator Colour of indicator changed from: Orange to Purple Titration No. 1(trial) 2 3 4 Final burette reading (cm3) 24.40 48.60 24.15 48.40 Initial burette reading (cm3) 0.00 24.40 0.00 24.15 Volume of titrant used (cm3) 24.40 24.20 24.15 24.25 Average volume: 24.20 cm3 Calculation: Number of mole of Kr2Cr2O7 = 1.2430 / [(7)(15.9994)+(2)(51.9961)+(2)(39.0983)] = 0.004225 ? Cr2O72- : Fe2+ = 1 : 6 ?
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Remember to fill the flasks completely with water without trapping any air bubbles. 2.> To one of the volumetric flask, add about 1 cm3 of MnSO4 solution well below the surface with a dropper. 3.> Similarly, introduce about 1 cm3 of alkaline KI solution to the same flask. Be sure that no air becomes entrapped and then invert the stopped flask to distribute the precipitate uniformly. 4.> When the precipitates has settled at least 2 cm below the stopper, introduce about 1 cm3 of conc.H2SO4 well below the surface.
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We prepared for the lab by obtaining all the necessary materials in the equipment list. 2. With the funnels, we poured 50mL of the following reactants: Acetone, HCL, and Iodine; in their respective burette. 3. In the Erlenmeyer flask, we carefully poured 10mL of Acetone from the burette, 10mL of HCL, and 20mL of distilled water. Once we had those three in the Erlenmeyer flask we poured 10mL of iodine and started the timing as soon as the iodine touched the three solutions.
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Therefore the following masses can be calculated: Mass number Substances Mass number calculation Mass calculation (g) Mass (g) 5 H2O 2 - 4.d) 40.34 - 39.67 0.67 6 FeSO4 3 - 5 1.48 - 0.67 0.81 To work out the formula of the FeSO4xH2O: Moles of FeSO4 Mr = 56 + 32 + (16 x 4) = 152 number of moles = mass Mr n = 0.81 = 0.00533 moles 152 Moles of H2O Mr = 18 n = mass n = 0.67 = 0.0372 moles Mr 18 Empirical formula To work out molar ratio of FeSO4 to H2O (value of x): 1 x 0.0372 = 6.98 0.00533 x = 6.98 therefore the formula is = FeSO4(H2O)7 Method 2 1.
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The choice of carrier gas is often dependant upon the type of detector which is used. The carrier gas system also contains a molecular sieve to remove water and other impurities. Sample injection port For optimum column efficiency, the sample should not be too large, and should be introduced onto the column as a "plug" of vapor - slow injection of large samples causes band broadening and loss of resolution. The most common injection method is where a micro syringe is used to inject sample through a rubber septum into a flash vaporizer port at the head of the column.
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