dertermining the rate equation essays

dertermining the rate equation essays Title: determination of the rate equation Task: Plan design and conduct an experiment to determine the rate equation for the reaction between Sodium Thiosulphate Na2S2O3 and Hydrochloric Acid HCl 2HCl(aq) + Na2S2O3(aq) 2NaCl (aq) + SO2(g) + S(s) + H2O(l) 0.4 mol dm-3 Sodium Thiosulphate Na2S2O3 10cm3, 25cm3, 50cm3 measuring cylinder 1. Measure out 50cm3 of sodium Thiosulphate using the 50cm3 measuring cylinder 2. Pour this into the 100ml conical Flask 3. The conical Flask should be placed on the paper with the x marked clearly on it. 5. add this to 22.5cm3 of distilled water 6. add this dilute mixture of HCl to the sodium Thiosulphate 8. record how long it takes for the cross to disappear 9. carry out the experiment again for the volumes mentioned in the table below (x) Initial Volume of water/ cm3 Initial Concentration of Dilute HCl/ Moles dm-3 Time taken/ Seconds Relative Initial Rate 1/t 0 25 x/ total volume * number of concentrations The concentrations that I have chosen to do vary from those that were done in the experiment because I wanted to see what would happen if I doubled the concentration of HCl and reduced the volume of water used, what affect it would have on the rate. In theory as initial concentration of HCl doubles or quadruples the initial rate should also double or quadruple. The volumes that I have chosen are shown above in the table. The amount of HCl and distilled water used always equals 50cm3 in total as it did in the demonstration. I have chosen o choose eleven different co ...

Rules for Assigning Oxidation Numbers

Rules for Assigning Oxidation Numbers Electrochemical reactions involve the transfer of electrons. Mass and charge are conserved when balancing these reactions, but you need to know which atoms are oxidized and which atoms are reduced during the reaction. Oxidation numbers are used to keep track of how many electrons are lost or gained by each atom. These oxidation numbers are assigned using the following rules. Rules for Assigning Oxidation Numbers The convention is that the cation is written first in a formula, followed by the anion. For example, in NaH, the H is H-; in HCl, the H is H.The oxidation number of a free element is always 0.  The atoms in He and N2, for example, have oxidation numbers of 0.The oxidation number of a monatomic ion equals the charge of the ion.  For example, the oxidation number of Na is 1; the oxidation number of N3- is -3.The usual oxidation number of hydrogen is 1.  The oxidation number of hydrogen is -1 in compounds containing elements that are less ​electronegative than hydrogen, as in CaH2.The oxidation number of oxygen in compounds is usually -2.  Exceptions include OF2 because F is more electronegative than O, and BaO2, due to the structure of the peroxide ion, which is [O-O]2-.The oxidation number of a Group IA element in a compound is 1.The oxidation number of a Group IIA element in a compound is 2.The oxidation number of a Group VIIA element in a compound is -1, except when t hat element is combined with one having a higher electronegativity.  The oxidation number of Cl is -1 in HCl, but the oxidation number of Cl is 1 in HOCl. The sum of the oxidation numbers of all of the atoms in a neutral compound is 0.The sum of the oxidation numbers in a polyatomic ion is equal to the charge of the ion.  For example, the sum of the oxidation numbers for SO42- is -2.