A primary standard must fulfill some preconditions: it must be readily available (check), not to have an outrageous price (check), have a good purity (check), have a long shelf life (check but only with the utmost care), have a stable concentration in solution (FAIL).
NaOH solutions do not last long unless they are kept under nitrogen, because they absorb very quickly CO2 from air which of course lowers the concentration.
So every now and then you must check their titre with an acidic primary standard or simply discard them; I can't recall at the moment how often we used to do that in my lab but it was of the order of once or twice a week.
A primary standard must fulfill some preconditions: it must be readily available (check), not to have an outrageous price (check), have a good purity (check), have a long shelf life (check but only with the utmost care), have a stable concentration in solution (FAIL).
NaOH solutions do not last long unless they are kept under nitrogen, because they absorb very quickly CO2 from air which of course lowers the concentration.
So every now and then you must check their titre with an acidic primary standard or simply discard them; I can't recall at the moment how often we used to do that in my lab but it was of the order of once or twice a week.
NaOH, sodium hydroxide, is used in titration of acids. Another base such as potassium hydroxide could be used; but, sodium hydroxide is common and readily available.
NaOH, sodium hydroxide, is used in titration of acids. Another base such as potassium hydroxide could be used; but, sodium hydroxide is common and readily available.
A primary standard must fulfill some preconditions: it must be readily available (check), not to have an outrageous price (check), have a good purity (check), have a long shelf life (check but only with the utmost care), have a stable concentration in solution (FAIL).
NaOH solutions do not last long unless they are kept under nitrogen, because they absorb very quickly CO2 from air which of course lowers the concentration.
So every now and then you must check their titre with an acidic primary standard or simply discard them; I can't recall at the moment how often we used to do that in my lab but it was of the order of once or twice a week.
A primary standard must fulfill some preconditions: it must be readily available (check), not to have an outrageous price (check), have a good purity (check), have a long shelf life (check but only with the utmost care), have a stable concentration in solution (FAIL).
NaOH solutions do not last long unless they are kept under nitrogen, because they absorb very quickly CO2 from air which of course lowers the concentration.
So every now and then you must check their titre with an acidic primary standard or simply discard them; I can't recall at the moment how often we used to do that in my lab but it was of the order of once or twice a week.
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NaOH, sodium hydroxide, is used in titration of acids. Another base such as potassium hydroxide could be used; but, sodium hydroxide is common and readily available.
NaOH, sodium hydroxide, is used in titration of acids. Another base such as potassium hydroxide could be used; but, sodium hydroxide is common and readily available.
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VOTE