(Introduction ,The Equipment ,The Process , Calculations ) Volumetric Analysis (Introduction ,The Equipment ,The Process , Calculations ) EXP./Preparation of a standard solution of sodium carbonate (Na2CO3) Prepared by: Hemn Khalid Qadir At March 2015 to 1st stage in college of pharmacy

Introduction *Volumetric analysis It is a general term for a method in quantitative chemical analysis in which the amount of a substance is determined by the measurement of the volume that the substance occupies. * It is commonly used to determine the unknown concentration of a known reactant. *Volumetric analysis is often referred to as titration, a laboratory technique in which one substance of known concentration and volume is used to react with another substance of unknown concentration.

The Equipment Volumetric analysis involves a few pieces of equipment that you may not have seen before: Pipette – for measuring accurate and precise volumes of solutions Burette – for pouring measured volumes of solutions Conical flask – for mixing two solutions Wash bottles – these contain distilled water for cleaning equipment Funnel – for transfer of liquids without spilling Volumetric flasks – a flask used to make up accurate volumes for solutions of known concentration

The Process - Preparation *Two solutions are used: The solution of unknown concentration; The solution of known concentration – this is also known as the standard solution *A standard solution is one whose concentration is known exactly. Standard solutions of liquids, for Example acids, are easy to prepare and are usually supplied. Standard solutions of solids can be prepared by weighing a mass of solid, and dissolving it in a known volume of solution in a volumetric flask. Today, you are going to prepare a standard solution of sodium carbonate to use later in another practical. *Clean all glassware to be used with distilled water. The pipettes and burettes will be rinsed with the solutions you are adding to them

CALCULATION Wt= M× M.wt ×V /1000 For solid substance we use this equation Wt= M× M.wt ×V /1000 *Anhydrous sodium carbonate (Na2CO3) has a molar mass of 106 g mol-1. A 0.1 M solution is made up, using a 250 cm3 volumetric flask. For 250 cm3 of 0.1 M sodium carbonate solution, the mass required is: 0.1 x 106 x 250 / 1000 = 2.65 g

Procedure 1.Using a balance, measure accurately 2.65 g of pure anhydrous sodium carbonate on a clock glass. 2.Slowly transfer the sodium carbonate with stirring, to about 50 ml of distilled water in a clean 250 ml beaker. To ensure that all the sodium carbonate is transferred, use a wash bottle to rinse the clock glass with deionised water, and add the rinsings to the beaker. 3.Continue stirring the mixture with a stirring rod until the sodium carbonate has fully dissolved. 4.Pour the solution into the 250 ml volumetric flask.

Procedure 5. Using a wash bottle, rinse out the beaker several times with D.W., and add the rinsings to the solution in the volumetric flask. 6. Fill the flask to within about 1 cm of the calibration mark, and then add the water drop wise, using a dropping pipette, until the bottom of the meniscus just rests on the calibration mark. 7.Stopper the flask and invert it several times to ensure ahomogeneous (evenly mixed) solution. 8.Label the flask.