density and weight of acids

[TATER]

hello, i was doing some experiments and managed to make some nitric acid and i don't know the percent. is there an easy way to determine the percent???also, the sulfuric acid i used to make it, i also had no idea what the percent was. if any body knows a highly effective way to determine the percent of the acid it would be great. thanks!!!

[Cap'n Refsmmat]

Find a base of a known concentration and add a measured amount to it until the pH hits 7. If you know how much acid you had, concentration of acid * its volume = concentration of base * its volume. I think.

 

More:

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

[John Cuthber]

This table gives density vs mole fraction for sulphuric and nitric acids.

http://www.kayelaby.npl.co.uk/chemistry/3_6/3_6_3.html

[TATER]

Find a base of a known concentration and add a measured amount to it until the pH hits 7. If you know how much acid you had, concentration of acid * its volume = concentration of base * its volume. I think.

 

More:

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

 

i have the acids, i have the phenolphthalein yet the process makes no freakin sense at all. can you help explain the process a bit ?? :confused:

also how can i figure the % of the acids from those charts?? thanks!!

[Darkblade48]

Titration is the process where, by adding a known amount and known concentration of (either) a base or acid to the other. By doing this, it allows you to calculate the concentration of the unknown.

 

For example, if you know the concentration and volume of sodium hydroxide you add to your unknown concentration (but known volume) of acid, then you can calculate the concentration of the acid. At a pH of 7, you know that there is no excess of acid or excess of base, and from there, with the amount of base added known, you can calculate the concentration of the acid.

[TATER]

thanks, but theres one thing missing, what do i do to calculate the percentage of the acid???i get the process but what do i do when the Ph is at 7???

[Cap'n Refsmmat]

First find the volume of the acid before you do it. Then, you can work out that

 

volume of acid * concentration = volume of base * concentration

 

So the acid's concentration is

 

volume of base * base's concentration

Volume of acid

[John Cuthber]

Don't forget that all the concentrations there have to be expressed as normality ie gram equivalents per litre (which is that same as molarity for nitric acid, but not for sulphuric).

 

 

Only bother to read the next bit if you would otherwise point out the error.

Strictly the units only need to be g eqiv / volume- it would still work in cubic feet but that's just complicating things.