When finding percent yield, what problem would occur if the precipitate isn\'t a

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When finding percent yield, what problem would occur if the precipitate isn't allowed sufficient time to settle from the solution? EXPERIMENT 1 2 An Estimation of Avogadro's Number I. OBJECTIVE: To calculate an approximate value of Avogadro's number. o x To II. DISCUSSION: Oleic acid (CH,CH,CH,CH CH CH-CH,CH,CH-CHCH,CH,CH.CH.CH,CH.CH,COOH), a major constituent of olive oil, is an organic acid that is soluble in alcohol, but insoluble in water is placed in water, it usually spreads out over the water surface creating a layer that is one A single drop of pure olcic acid could easily cover the surface of a large swimming pool. For this reason a very dilute alcohol solution of the acid must be used in this experiment When the acid molecule thick The oleic acid molecule is roughly cylindrical in shape. The COOH end of the oleic acid is polar, while the long chain of carbons and hydrogens is nonpolar and is repelled by water. When applied to water, the molecules arrange themselves so that they float upright in the water. This is due to an attraction betwecn the polar end of the oleic acid molecule and the water molecules, and a repulsion of the hydrocarbon end toward the water. If hydrochloric acid is added to the water, this attraction is destroyed and the olcic acid molecules float instead, on their sides. This makes the oleic acid spot larger By measuring the diameter of the oleic acid spot, first in water, and then in water with HCl added, an approximate value for Avogadro's number can be calculated. III. MATERIALS A large plastic tray, ruler, concentrated hydrochloric acid, 10 mL and 100 mL graduated cylinders lycopodium powder, and a solution of oleic acid in alcobol (3.0 cm' of oleic acid in 1000 cm of solution) IV. PROCEDURE: A. Measuring an Oleic Acid Spot in Water I. Thoroughly clean a large plastic tray with soap solution and then rinse it well with tap water so that no soap remains Dust the water surface lightly with tycopodium 2. Pour water into the tray to a depth of about 1 cm. powder You are now going to put a drop of oleic acid solution on water and then on acidified water. For best results, the manner in which you apply the drop should be the same for both applications. In both cases, hold the dropper at the same angle and at the same distance from the water in the tray.

Explanation / Answer

1. The powder should have very low oil absorption value and more hydrophilic. So that, the powder will absorb alcohol easily and this is distributed in to the water phase. While, the oil is gently pushing the powder outwards so that the oily layer hase definite shape and hence the error arising during measurements of area can be minimised.

2. Thickness of the oily layer will increase and volume of the molecule would increase. Therefore, the avacadro number will decrease.

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