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Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: s.wagner281 on March 21, 2012, 03:30:38 AM

Title: Help understanding/setting up titration problems
Post by: s.wagner281 on March 21, 2012, 03:30:38 AM

I am struggling a lot with realizing what exactly is occuring and how to set up a titration equation

For use in titrations, we wish to prepare 17L of HCl(aq) with a concentration known to four significant figures. This is a two-step procedure beginning with the preparation of a solution of about 0.10 M HCl . A sample of this dilute HCl(aq) is titrated with a NaOH(aq) solution of known concentration.

How many milliliters of concentrated HCl(aq)(d = 1.19g/mL ; 38%HCl by mass) must be diluted with water to 17 L to prepare 0.10 M HCl?

I'm not looking for an answer, simply looking for help in setting up what is occuring and just comprehending whats happeneing. I don't understand the 2 step part of the equation, nor how to set up an equation for any

Title: Re: Help understanding/setting up titration problems
Post by: Borek on March 21, 2012, 03:46:53 AM

I don't understand what is your problem. What you wrote suggests you have troubles understanding the procedure in general, but the only real question you posted is related to simple concentration calculation and conversion between %w/w and molarity.

Title: Re: Help understanding/setting up titration problems
Post by: w4rlock on March 21, 2012, 04:17:20 AM

As for the concentration of HCl:
Start by calculating the number of moles of HCl per mL of concentrated HCl solution (using the 38%, the density of the solution and the RMM of HCl).
You need 0.10 moles per litre to make a 0.10 M so how many mL of this will give you 0.10 moles of HCl? Multiply that by 17.