needs help with these questions from prac (standard solution)

[123456k]

why is solid sodium hydroxide not used as a primary standard when standard solutions of bases are required?
because its an acid? not sure

name another bacis substance which is suitable for use as a primary standard
potassium hydrogen phthalate KH(C8H4O4)?

how would the accuracy of the standard solution be affected if the volumetric flask had been rinsed with de ionised water before use and droplets of water were left in the flask when the sodium carbonate was added?
not sure

[vea]

Why is solid sodium hydroxide not used as a primary standard when standard solutions of bases are required?
NaOH is not used as a primary standard because it absorbs H20 and reacts with CO2 in the atmosphere.

Name another bacis substance which is suitable for use as a primary standard
Na2CO3

How would the accuracy of the standard solution be affected if the volumetric flask had been rinsed with de ionised water before use and droplets of water were left in the flask when the sodium carbonate was added?
If there were droplets of water left in the flask when the sodium carbonate was added, that would mean that the sodium carbonate would have been diluted with water, thus lowering its concentration.

[123456k]

do you have one other than na2co3 because thats the primary standard we're using to prepare a stansard solution.

[jane1234]

How would the accuracy of the standard solution be affected if the volumetric flask had been rinsed with de ionised water before use and droplets of water were left in the flask when the sodium carbonate was added?
If there were droplets of water left in the flask when the sodium carbonate was added, that would mean that the sodium carbonate would have been diluted with water, thus lowering its concentration.

Also, the titre would be less than it should be... as less acid would be required to react with diluted sodium carbonate.

[jane1234]

do you have one other than na2co3 because thats the primary standard we're using to prepare a stansard solution.

Found this one:

tris-(hydroxymethyl)aminomethane (TRIS or THAM): (CH2OH)3CNH2

[nacho]

why is solid sodium hydroxide not used as a primary standard when standard solutions of bases are required?
because its an acid? not sure              NOTE: YOU SHOULD BE FAMILIAR WITH SODIUM HYDROXIDE AS A STRONG BASE!!

name another bacis substance which is suitable for use as a primary standard
potassium hydrogen phthalate KH(C8H4O4)?    <---- this is an acid

most of these questions are answered in the textbook
but, to answer your first question:
To be a primary standard, something has to be:
- non-volatile or reactive
- economic
- have a high molecular mass
- have an accurately known concentration
and there's a few more,

Basically, sodium hydroxide absorbs acidic oxides from the air,
this means that it's weight will be increasing, even as it is own the weighing scales.
Because of it's increasing weight, you cannot know it's concentration for sure, and cannot use it as a primary standard.

[123456k]

how do you know that potassium hydrogen phthalate KH(C8H4O4) is an acid nacho?

[nacho]

how do you know that potassium hydrogen phthalate KH(C8H4O4) is an acid nacho?

this is actually just what i've read before.
although there is a way to determine whether something is capable of giving/receiving H+ protons, i'm not ENTIRELY sure of how to explain it, i can get back to you if i find out. ill look into it.
something to do with either:
Hydrogen bonds / dipole dipole attraction or electronegativity..  sorry can't help you atm

[Mao]

how do you know that potassium hydrogen phthalate KH(C8H4O4) is an acid nacho?

this is actually just what i've read before.
although there is a way to determine whether something is capable of giving/receiving H+ protons, i'm not ENTIRELY sure of how to explain it, i can get back to you if i find out. ill look into it.
something to do with either:
Hydrogen bonds / dipole dipole attraction or electronegativity..  sorry can't help you atm

http://en.wikipedia.org/wiki/Potassium_hydrogen_phthalate

In water this will give the first-deprotonated conjugate of phthalic acid, acidic due to the carboxyl group.

[nacho]

how do you know that potassium hydrogen phthalate KH(C8H4O4) is an acid nacho?

this is actually just what i've read before.
although there is a way to determine whether something is capable of giving/receiving H+ protons, i'm not ENTIRELY sure of how to explain it, i can get back to you if i find out. ill look into it.
something to do with either:
Hydrogen bonds / dipole dipole attraction or electronegativity..  sorry can't help you atm

http://en.wikipedia.org/wiki/Potassium_hydrogen_phthalate

In water this will give the first-deprotonated conjugate of phthalic acid, acidic due to the carboxyl group.

seeing that the carboxyl functional group is more related to AOS 2, would there be any knowledge which we have acquired up until now to determine this?
I dont know why, but the terms i mentioned above seem to be speaking to me, I vaguely remember being told that they had something to do with this.

[123456k]

How would the accuracy of the standard solution be affected if the volumetric flask had been rinsed with de ionised water before use and droplets of water were left in the flask when the sodium carbonate was added?

ive read this question very carefully and i have concluded that the accuracy may increase. by rinsing the volumetric flask with the de ionised water the possibilty of having impurities would be canceled. however having the droplets of water left in the flask would have no overall effect because the solution used to rinse the flask is also used to fill the volumeteric flask. later on de- ionised water needs to be added the volumetric flask until it reaches the calibration line thus a standard soultion is achieved. therefore the concentration wouldn't be affected.

before you guys said it could lower the concetration.

could someone clarify this for me?