To determine relative molecular mass of a soluble base, X2CO3 by carrying out an acid-base titration with the following reaction , knowing the amount of hydrochloric acid used and the amount of substance Z used. Hypothesis: The X in substance Z is a group 1 element because substance Z is a soluble metal carbonate and would most likely be sodium or potassium because these elements are commonly used. Materials
100 cm3 beaker, 250 cm3 beaker, 250 cm3 volumetric flask with stopper, filter funnel, glass pipette, glass rod, de-ionized water, Substance Z, 25 cm3 bulb pipette, pipette filter, 250 cm3 conical flask, burette, burette stand & holder, 0. 1225 M hydrochloric acid, methyl orange indicator. Procedure: Part 1: Making a standard solution of substance Z 1. About 1. 3 g to 1. 7 g of substance Z was weighed out into the 100 cm3 beaker . 2. The 100 cm3 beaker and its contents were reweighed accurately and the mass was recorded in table 1. 3.
The contents of the 100 cm3 beaker were transferred into the 250 cm3 beaker. 4. The 100 cm3 beaker was weighed again and the mass w of the beaker was recorded. 5. De-ionized water was added cautiously down the side of the large beaker. About 150 cm3 of water was used, swirling the beaker to mix the contents. 6. A glass rod was used to stir the solution to dissolve the solid completely. 7. The solution was carefully transferred into the volumetric flask using the funnel, making sure that every drop of the solution goes into the volumetric flask.
8. The beaker, glass rod and funnel were washed several times using de-ionized water from the wash bottle, letting the washings go into the volumetric flask. 9. Carefully, more de-ionized water was added to just below the calibration line on the volumetric flask. A teat pipette was used to add the final drops of water until the level was reached. 10. The volumetric flask was stoppered firmly and shaken thoroughly to ensure that the solution is homogenous. Part 2: Titration to determine the relative molecular mass of substance Z. 11.
The burette was cleaned with de-ionized water and then with standard 1. 225 M hydrochloric acid to be used for the titration. 12. Using a bulb pipette, 25 cm3 of Substance Z was transferred into a clean conical flask. 13. A few drops of methyl orange indicator was added. 14. The substance Z solution in the conical flask was titrated with standard hydrochloric acid after the initial reading of the burette was recorded. The end-point of the titration was reached when the solution just changed from yellow to pink. 15. The final reading of the burette was recorded.