Notes On Gaseous State This page provides you all details about the gaseous state of BSc standard. Concerned problems will be solved at the end of each concept. Continue till the end to find the easiest explanation of every concept you need in this regard . Postulates of Kinetic Theory of Gases: 1. All gas consist of a very large number of minute particles, called molecules. 2. The gas molecules are extremely small in size and are separated by large distance. The actual volume of the gas molecules is thus negligible as compared to the total volume occupied by the gas. 3. The pressure exerted by the gas is due to the bombardment of the molecules on the walls of the vessel. 4. The gas molecules collide with one another and also with the walls of the vessels. These collisions are perfectly elastic and there is no loss of energy during these collisions. 5. The distance between the gas molecules are very large. Thus, there is no effective force of attraction or r
GE - I (Generic Elective) Chemistry Practical Experiments
1. Estimation of Oxalic Acid by titrating it against standard KMnO4 Solution (0.098 N).
Principle: The reaction between oxalic acid and potassium permanganate is an example of redox (oxidation reduction) titration. KMnO4 acts as the oxidising agent and oxalic acid as the reducing agent. They react as per the following reaction:
2KMnO4 + 3H2SO4 ------->
K2SO4 + MnSO4 + 5O
H2C2O4.2H2O + O ---------> 2CO2 + 3 H2O
Thus the equivalent mass of oxalic acid is equal to half of its molecular mass, i.e., 126/2 = 63.
The given oxalic acid solution is taken in 100 ml standard measuring flask and made up to the mark with water. It is then titrated against standard KMnO4 solution. From the volume of KMnO4 solution and Oxalic acid solution and the normality of KMnO4 solution the normality of oxalic acid solution is determined from which the amount of oxalic acid in whole of the supplied solution is calculated.
Procedure: The whole of the supplied oxalic acid solution was transferred to a 100 ml standard measuring flask by washing the content in the bottle several times. 10 ml of dilute H2SO4 was then added to the measuring flask. The volume in the flask was made up to the mark with water and well shaken. 10 ml of this was pipetted out into a flask and about 10 ml of dilute H2SO4 was added to it. This was then heated to a bearable temperature and the hot solution was titrated against standard KMnO4 solution.
Tabulation:
OR
Calculation: N1V1 = N2V2
(Normality equation)
10 ml of dilute acid solution is equivalent to 9.5 ml of 0.098N KMnO4 solution.
Hence normality of oxalic acid solution = (9.5 X 0.098) / 10 = 0.0931 N
Milliequivalent of oxalic acid in 100 ml solution = 0.0931 N X 100 = 9.31
Milliequivalent of oxalic acid in 100 ml solution = 0.0931 N X 100 = 9.31
Equivalent mass of oxalic acid = 63
Mass of oxalic acid in whole diluted solution = 9.31 X 63 = 586.53 milligram = 0.58653 gram
Conclusion: Mass of the oxalic acid in the supplied solution is 0.58653 gram
2. Identify the extra element present in the supplied compound marked _____________.
Principle: Elements like Nitrogen, Sulphur and halogens present in organic compound can be detected by Lassaigne's Test. In this test a piece of sodium reacts with the organic compound and the elements present in the compound are converted into the ionic form.
Na + C + N ======> NaCN
2Na + S =======> Na2S
Na +X =======> NaX (X = Cl or Br or I)
The ionic salts thus formed are are extracted by boiling water which is called the sodium fusion extract.
Preparation of Lassaigne's Filtrate: A small piece of Na was taken in a fusion tube and heated till shining. Pinch of organic compound was added to the tube. The tube was heated first gently than strongly. The red hot portion of the tube was dipped into the distilled water kept in a china mortar. The content in the mortar was crushed with a pastle and heated to boiling. The insoluble part of the was removed by filtration. The filtrate is known as Lassaigne's Filtrate.
Detection of Nitrogen:
Experiment: A pinch of the organic compound was heated with soda lime in a test tube. A glass rod dipped in concentrated HCl was then shown to the evolved gas. Also the evolved gas was passed through Nessler's reagent.
Observation: A gas with punget smell evolved which on contact with conc. HCl formed white fumes. The evolved gas when passed through Nessler's reagent formed brown ppt.
Inference: Nitrogen was predicted
Confirmatory test for nitrogen:
Experiment: 2 ml of L.F was taken in a test tube to which 2 ml of freshly prepared ferrous sulphate solution was added and heated. 2-3 drops of ferric chloride solution was then added and finally conc. HCl was added.
Observation: A Prussian blue coloration formed.
Inference: The presence of nitrogen was confirmed in the organic compound.
Detection of Sulphur:
Experiment: 2 ml of L.F was acidified with 2/3 drops of acetic acid and 1 ml of lead acetate solution was than added to it.
Observation: No black precipitate formed
Inference: Sulphur was absent
Experiment (Sodium nitro prusside test for sulphur): To 2 ml of L.F few drops of odium nitro prusside solution is added.
Observation: No purple violet colour formed.
Inference: Sulphur was absent
Detection of halogens:
Experiment: To 2 ml of L.F, 1 ml of conc. Nitric acid was added and then boiled for about a minute and then silver nitrate solution was added.
Observation: No white, yellow or pale yellow ppt. was formed.
Inference: Chlorine bromine and iodine were absent.