question:
1. Why are sodium hydroxide and hydrated sodium carbonate not suitable to be used as "primart standard "?
2. Why is it necessary to rinse the pipette with the standard carbonate ?
3. Explain whether the rinsing of conical flask with the standard sodium carbonate would lead to experimental error ?
titration
2007-10-01 10:23 pm
回答 (2)
2007-10-03 8:02 am
✔ 最佳答案
1.NaOH absorb water moisture and so its mass will increase gradually during weighing.Hydrated Na2CO3 is efflorescent(loss of water) and its mass will increase gradually during weighing.2.Because if not,water will be remained in the pipette.The sodium carbonate will be dilute.The concentration of the solution decrease.
3.It will lead to experimental error.Because if we rinse the conical flask with Na2CO3,some of Na2CO3 will be remained in the conical flask.The number of mole of Na2CO3 will increase,so the volume of HCl will increase for reaction.The concentration of Na2CO3 solution will be higher than real.
參考: me
2007-10-01 10:51 pm
1. they will absorb carobn dioxide and water in the water while exposed in air
2. to ensure the molarity unchanged
2. to ensure the molarity unchanged
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