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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
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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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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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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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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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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+ 6H2O Percentage Yield Calculation (NH4)2Fe(SO4)2.6H2O --> 2K3(Fe(C2O4)3) + 6H2O Molar ratio 1 : 1 Actual Yield 4.86g mol= 0.0128 mol -1 mol= 0.0128 mol -1 mass= 5.03g mass=6.28g GFM= 392g GFM= 491.1 Mol= mass/GFM Mass= GFM x mol Mol=5.03/392 Mass= 491.1 x 0.0128 Mol= 0.0128 Mass= 6.28g Theoretical Yield = 6.28g Percentage Yield =Actual Yield x 100 Theoretical Yield = 4.86g x 100 6.28g = 77.39% Discussion a) Reasons for the fact the yield of Potassium Trioxalatoferrate are less than 100% are: * Products may be lost during the decanting stage * Products may be washed away * Products may be left on filter paper * Products may react with chemicals in the beakers from previous experiments b)
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of empty boat after = 26.88g - 1.926g = 24.954g Now that I have the mass of the crystals used I will be able to calculate the number of moles of CuSO4 that I have by using the equation: Number of moles = Mass Molar Mass n = m Mr n = 24.954 249.6 n = 0.099975961 mol Now I know how many moles of CuSO4 I have I can work out the concentration of the solution (CuSO4.5H2O)
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The volumetric flask was shaken upside down for several times. 5. 25.0 cm3 of sodium carbonate solution was pipetted into a conical flask. 6. 3 drops of methyl orange indicator was added into the conical flask. 7. Hydrochloric acid was poured into a burette. 8. The initial burette reading was recorded. 9. The reaction mixture in the conical flask was titrated with hydrochloric acid until it just changes from yellow to orange. 10. The final burette reading was recorded.
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= c � v = 0.1 � 0.02945 n = 0.002945 mol n(CH3COOH) = 0.002945 mol (n(NaOH) and n(CH3COOH) are a 1:1 ratio) m = n mr mass(CH3COOH) = 0.002945 � 60 = 0.1767 grams The mass of ethanoic acid in the sample of Aceto vinegar is: 0.15906g n(NaOH) = c � v = 0.1 � 0.02651 n = 0.002651 mol n(CH3COOH) = 0.002651 mol m = n mr mass(CH3COOH) = 0.002651 � 60 = 0.15906 grams The mass of ethanoic acid in the sample of Cornwalls vinegar is: 0.15906g n(NaOH)
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Unless this test is carried out immediately after the flexural strength test on the beam, the broken portions should be returned to the curing tank until required. c. Place the broken portion of the beam in the test jig as per the sketch. d. Place the jig centrally in the compression test machine (no packing is to be used between the specimen and the auxiliary platens or between the compression machine platens and the auxiliary platens).
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The dimensions of the three cubes were measured with calipers. No "under size" or "oversize" cubes were recorded. 5. The cubes were weighted 6. Test machine platen was wiped with a dry cloth. 7. The cube was placed centrally on the lower platen of the test machine with the rough as-cast top surface of the test cube vertical not in contact with the platens. 8. The appropriate loading rate was selected for the cube tested. Pacerate for 150mm cubes is 338kN / min.
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By using the mass change one can determine the percent of the hydrate. Hypothesis: For this lab I made two hypothesis'. The first one states that in the CuSO4* 5H2O; a majority of the compound is cupric sulfate rather than the hydrate. The second one states that the NaCl is already a anhydrous compound based on the fact there wasn't really any significant mass change after heating. Materials and Equipment: 1 hot plate 1 evaporating dish 1 glass stirring rod 1 crucible tongs cupric sulfate pentahydrate (CuSO4* 5H2O)
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The predicted mass of CuO is 0.72g. The second hypothesis is the theoretical yield of copper from the second reaction. As demonstrated below - Materials and Equipment: (From Handout) 1.00g Cu2(OH)2CO3 copper(II) carbonate basic 0.50g C carbon black ring stand with ring clamp and clay triangle crucible and lid crucible tongs 2 weigh boats glass stir rod metal spatula gas burner and hose igniter 50 ml beaker hot plate Procedure (from handout) Part 1 1. Mount an iron ring on a ring stand, equip with a clay triangle and obtain a Bunsen burner, crucible and cover.
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Titrations are important to understand how acids and bases react with each other, ways to understand detection of experimental error, and to experimentally calculate or figure out what a chemical or substance consists of or the properties it can contain. Titrations are a key tool in industry laboratories and for educational purposes. The right technique and precision of an experiment, accurate results can be achieved. Accuracy and precision can improve in a titration when effort as well as repetition is applied.
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The hydrogen atom is left with a slight positive charge as electrons exist further away from it due to the presence of chlorine in the molecule. Instantaneous Dipoles Many small molecules do not possess permanent dipoles because the atoms that are bonded together all have the same, or very similar, electronegativity. This means that on average, the shared electron cloud is evenly distributed across the atoms. However, a temporary or instantaneous dipole can arise because the electrons are in constant motion and at any particular moment, they may not be evenly distributed over the atoms in the molecule.
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It is mostly used in medicine like pain killers and also they are used for reducing fever. Aspirin is made by reacting salicylic acid with acetic anhydride. The human generation already knew how useful salicylic acid for pain. It was until the 19th century when we learned how to make mass production of aspirin and how to cope with the toxic side effects. Aspirin has many pharmaceutical uses; the most important is the cure for any kind of pain. It can also treat arthritis because it has an anti-inflammatory effect and also reduce fever. One of the majors side effects gastritis this gives stomach aches.
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It has an electron shell of 2, 8, 18, and 1 - and is an excellent conductor of electricity. HYPOTHESIS It is to be expected that there will be a loss in weight at the end of the experiment. SAFTEY ASSESMENT Tying hair back Can catch alight with the Bunsen flame, and gets in the way of working. Goggles Must be worn, as liquids are being used. They protect the eyes from any splashes. Bunsen burner Ensure that the hole is closed, keeping a visible flame for when the Bunsen is not in use. Lab coats Worn to protect clothes Bags and stools Keep them both tucked under tables or moved out of the way for a clear fire exit, and to prevent falling over them, etc.
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The mobile phase is a developing liquid. The developing liquid (Butyl Ethanolate), travels up the stationary phase, moving the samples with it, in this case over the counter analgesics. The samples will separate on the stationary phase according to how much they absorb on the stationary phase against how much they dissolve in the mobile phase. Hypothesis It is to be expected that substance x will be able to be identified using thin layer chromatography. Safety assessment Goggles Prevents from any splashes getting in the eyes. Lab coats Prevents staining of clothes.
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& pressure (1atm), 1 mole of gas = 24000cm3 So if the equation 1 is correct, then volume of gas given off = 0.0037 � 24000 = 89cm3 Equation 2: Ratio of - CuCO3 : CO2 1 : 1 Mass of 1 mole of CuCO3 = 123.5g Mass of Copper Carbonate used = 0.4g Moles of CuCO3 = 0.4 � 123.5 = 0.003 moles As the ratio is 1:1, so moles of gas given off = 0.003 moles At room temperature (20�c)
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The benzoic acid was dissolved with minimum amount of boiling water, and the solution was allowed to cool down to initiate the formation of the crystals. 8. The crystals were obtained by suction filtration and were dried in an oven for 1 night. 9. The dried crystals were weighed and its melting point range was determined. Data and Calculation 1. The gas evolved in step 4: NH3 Test: the steam was directed to a piece of pH paper to measure the pH.
- Word count: 850