Standard Volumetric Flasks

A dilute standard solution can also be made by carefully diluting a more concentrated standard solution. In this instance, a known volume of the concentrated standard solution is delivered into a standard volumetric flask, and the solution diluted to the graduation line with deionized water. Pipettes are designed to deliver specific volumes of liquid. They can contain various volumes (from 0.50 to 200 cm ) and the volume of the pipette is marked on its bulb or shown by graduation marks on the side of the pipette (Fig. 9.2). 

Alloy solutions were prepared by dissolving 0.2-0.5 g of the standard alloys in about 15 ml cone. HCl and 2-4 ml cone. HNO3 by heating on a water bath. The solution was evaporated nearly to dryness, another 10 ml of cone. HCl was added to it, diluted with water, filtered and made up to 50 ml in a standard volumetric flask (182). 

Aluminon solution - dissolve each of the following reagents in a minimum volume of distilled water 7 g ammonium acetate AR grade, 2.5 cm concentrated hydrochloric acid, AR grade, 0.2 g aluminon reagent, 0.5 g gum acacia. Transfer the solutions in the above order to a 500 cm standard volumetric flask and dilute to the mark with distilled water. 

Pipette an aliquot of the test and blank solutions (maximum 35 cm ) into two separate 50 cm standard volumetric flasks. If the volume added is less than 35 cm then adjust the volume to 35 cm. Add 5 cm of Tiron to each flask and neutralize to Congo red paper with 50% ammonia solution. Add 5 cm of sodium acetate-acetic acid buffer solution (pH 4.7) and dilute to 50 cm with distilled water. 

Transfer an aliquot of the sample and blank solutions (maximum 40 ml) into two separate 50 cm standard volumetric flasks and add 0.2 cm of thioglycollic acid. 

Into six 50 cm standard volumetric flasks pipette the following volumes of standard 5 ug/ cm titanium solution. 

Transfer the solutions to 1 cm cells and read off the optical density at a wavelength of 410 nm using the solution containing no titanium as the reference solution. Plot a graph of optical density against ug of titanium contained in the 50 cm standard volumetric flasks. 

Pipette 10 cm of the 100 ug/ cm iron solution into a 100 cm standard volumetric flask and dilute to the mark with 0.2 nitric acid solution, mix thoroughly. This solution contains 10 ug/Fe/ cm. ... 

Add the required volume of 0.2 M nitric acid solution to make the volume of each solution 40 cm. Add 5 cm of 0.880 ammonia solution and check that the solution is alkaline to litmus paper. Dilute to 50 cm with distilled water and mix thoroughly. Measure the optical density of the solutions. Transfer the solutions to 4 cm glass cells and read off the optical density at a wavelength of 535 nm using the solution containing 0 ug iron as the reference solution. Plot a graph of optical density against ug of iron present in the 50 cm standard volumetric flask. 

Periodic acid (0.01 M) weigh out 2.28 g of periodic acid (HIO4.2H2O) to four decimal places, and dissolve in approximately 100 ml of distilled water. Transfer quantitatively to a 1 litre standard volumetric flask, dilute to the mark and mix thoroughly. 

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