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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.
- Word count: 1648
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.
- Word count: 776
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.
- Word count: 1781
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.
- Word count: 6928
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.
- Word count: 5388
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.
- Word count: 671
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)
- Word count: 1042
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.
- Word count: 463
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.
- Word count: 846
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.
- Word count: 804