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Title: What is the dilution factor in this case? Post by: dave on Nov 19, 2012 Procedure:
1. pipette 25ml of calcium gluconate injection solution and 5ml of standard MgSO4 (0.05M) solution into a conical flask, add 1/4 small spatula spoon of eriochrome black T indicator and 10 ml of the ammonia buffer, which is provided in a dispenser. 2. Record the initial volume of disodium edetate solution before titragluconate and MgSO4 mixture until the end point colour change is observed. Record final volume of disodium edetate solution. 3. Repeat titration two times and calculate the average molarity of the calcium gluconate injection solution. the 3 titrations: V2-V1 (ml): 16 21.2 25.5 The question asks: Calculate the percentage (weight/volume) of CALCIUM in the calcium gluconate injection solution. Note: calcium gluconate injection solution used for titration has been diluted. Record dilution factor and adjust your calculations accordingly. Title: What is the dilution factor in this case? Post by: Firedancer20 on Nov 19, 2012 It looks like the dilution factor is a piece of data that was given to you, but you missed. You can only figure the calcium concentration for the solution you were given. It's my guess that the teacher realized that at the original concentration the titration volumes would be too low to be accurate, and so diluted by a certain amount to result in more practical and reproducible titration volumes. Go ask your instructor; if you are lucky the dilution factor was 10.
Also, your lab reproducibility is poor. For any lab titration, you should have random variance of .2 ml, tops. If you can, go back and redo. |