ATAR Notes: Forum

VCE Stuff => VCE Science => VCE Mathematics/Science/Technology => VCE Subjects + Help => VCE Chemistry => Topic started by: sam0001 on June 09, 2012, 01:00:01 pm

Title: backtitration!
Post by: sam0001 on June 09, 2012, 01:00:01 pm

probably a silly question, but how do you choose an indicator for a back titration?

example ammonia titrated with hcl, and then the hcl titrated with naoh.

Title: Re: backtitration!
Post by: Tonychet2 on June 09, 2012, 01:18:09 pm

choose an indicator for the second titration between hcl and naoh

so u can get the end point between hcl and naoh to determine how much hcl was in excess, therefore an indicator for the first titration wouldnt be required

Title: Re: backtitration!
Post by: aznxD on June 09, 2012, 01:40:56 pm

Quote from: sam0001 on June 09, 2012, 01:00:01 pm

probably a silly question, but how do you choose an indicator for a back titration?

example ammonia titrated with hcl, and then the hcl titrated with naoh.

The reaction between ammonia and HCl is not a titration. Your just reacting the ammonia with excess HCl. Hence you pick an indicator suitable for the titration between the excess HCl and NaOH, so you can determine the amount of HCl in excess.