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Introduction

Determine the formula of hydrated Sodium Carbonate Na2CO3.x H2O is the formula for hydrated Sodium Carbonate, where x represents the number of water molecules present in the crystals. The first method I will use to determine x, will involve heating the crystals. When the crystals are heated, they readily effloresce to form a white powder, the anhydrous form Na2CO3 1. Hydrated Sodium Carbonate Spatula Scales (accurate to 3 d.p.) Bunsen burner Crucible and lid Pipe Clay Triangle Tripod Heatproof mat Long handled tongs Safety goggles Tub and lid Mass of crucible and lid (g) Mass of crucible lid and crystals (g) Mass of crucible, lid and anhydrous solid after 1st heating (g) Mass of crucible, lid and anhydrous solid after 2nd heating (g) A B C D Draw the above table * Using accurate scales, record mass of crucible and lid to three decimal places in the table under A * Approximately weigh 5.000g hydrated Sodium Carbonate crystals into a tub * Transfer the crystals from tub to empty crucible and weigh with lid * Record mass under B * Gently heat crucible and contents with lid on, ...read more.

Middle

Volume of HCl used in 1st titration (cm3) Volume of HCl used in 2nd titration (cm3) Average volumes of both titers (cm3) A B C D E F G If I assume that x = 5, the molar mass of Na2CO3.xH2O would be 196gmol-1. A solution of 1M HCl should be used. The mole ratio states that, HCl: Na2CO3 = 2:1, therefore a standard solution of around 0.5M Na2CO3 should be used to give rational titres. The experiment is to be carried out a number of times; therefore a 100cm3 standard solution of 0.5M Na2CO3 will be adequate for 4 trials. Therefore the mass of hydrated Sodium Carbonate required for the titration will be: 0.5M x 18gmol-1 = 98g 98g x (100cm3 / 1000cm3) = 9.8g Therefore 9.8g Na2CO3.xH2O will produce a standard solution of 0.5M, when added to 100cm3distilled water. When pH is below 8.2, phenolphthalein indicator is colourless. When above pH 10.0, the indicator turns pink 2. * Draw above table Firstly a standard solution of hydrated Sodium Carbonate is required * Rinse volumetric flask (100 cm3) ...read more.

Conclusion

of jet * As titration reaches end point, allow one drop of HCl out of jet, and spray end of jet with distilled water * When end point is reached, it will be accurate to one drop of HCl * Record volume of HCl under E * Repeat above until two results within 0.1cm3 are obtained and record the 2nd volume of HCl under F Safety goggles must be worn at all times during both experiments to ensure that no Sodium Carbonate or Hydrochloric acid comes into contact with the eyes. If there is contact, immediately rinse out eyes with water. If acid comes into contact with skin, rinse off immediately. 0.1M HCl will be used because a more concentrated solution may be hazardous. When bunsen's are not being used, they should be placed on the yellow 'safety' flame, so they are visible. All mass that are recorded must be to 3 decimal places to ensure a high grade of accuracy. All volumes that are recorded must be to 2 decimal places. 1 http://en.wikipedia.org/wiki/Sodium_carbonate 2 http://en.wikipedia.org/wiki/Phenolphthalein ?? ?? ?? ?? Adhal Mahmood 1 Centre Number: 30545 Candidate Number: 5540 ...read more.

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