Sciencemadness Discussion Board

math equation question

gardul - 21-10-2014 at 05:57

Good morning,

I think I have been using the wrong equation for a few things. What I need is to figure out how much HLC is in 100ML. but the solution is only 14% HCl the rest is Water and other impurities.

Below is what I have been using.

Grams of HCl = 14wt% x 100ml / (100 - 14) = 16.27g

is this the correct formula for this? thank you for any help.

woelen - 21-10-2014 at 06:56

No, this is not the correct formula.

You need to look up the density of 14% HCl by weight. This will be larger than 1 gram/ml, albeit not that much larger.

Then multiply the density (call it d) as follows: 0.14 * V * d, where V is the volume in ml and 0.14 is due to the 14% by weight.

Roughly estimating I would say appr. 15 grams per 100 ml, but please do the math more precisely by looking up the density.

gardul - 21-10-2014 at 07:42

Thank you very much. Knew I was messing it up. Your help is much appreciated.

EDIT:

0.14 * 100 * 1.0675 = 14.945g of 14%HCl per 100ml

This seems a little more correct. And would explain why a lot of my results are severly lacking. I want to say thank you again.

[Edited on 21-10-2014 by gardul]

[Edited on 21-10-2014 by gardul]

kmno4 - 21-10-2014 at 07:59

A tip:
To calculate density of given percentage (wt), not very diluted HCl aq , it is useful to know that: if your HCl has XY percentage, then its density is 1 + 0,01*0,5*XY.
For example, 10% HCl has density 1,05g/cm3; 20% has 1,10 g/cm3;
18% has 1,09; 30% has 1,15... etc.
It is approximation, but rather good.

gardul - 21-10-2014 at 08:18

Quote: Originally posted by kmno4  
A tip:
To calculate density of given percentage (wt), not very diluted HCl aq , it is useful to know that: if your HCl has XY percentage, then its density is 1 + 0,01*0,5*XY.
For example, 10% HCl has density 1,05g/cm3; 20% has 1,10 g/cm3;
18% has 1,09; 30% has 1,15... etc.
It is approximation, but rather good.


Thank you for this tip.