[always smile]

Is there any special rule for this type of titration?
I have 300 ml 0,1 M NH4OH in the glass, and I am adding 1,2 M HCl...after 25 ml it should be end of titration..
In the begining conductivity is growing up.
After 25 ml it should have faster growth (because there is  excess of HCl in the glass) but in my experiment it did not. Conductivity continues to grow as slow as in the begining...
I cheked pH  after I have added 25 ml of 1,2 M HCl, and it still vas high, about 11..
I try it a lot of times, but every time I got the same results..
I can not figure what is wrong??? Obviously I make the same mistake every time, but I can not figure what is wrong..
Can anyone help me please?
( I have used magnetic mixer during experiment)

[Borek]

Try to change volumes, perhaps concentrations are not what you think they are. Take less ammonia solution, titrate up to 50 mL of HCl, this kind of things.

[always smile]

I made solutions, so concentrations should be correct.. ( Only if it is not correct concentration which is written on original bottle ).
I had doubts, but I repeated a lot of times..
I can not find a logical explanation why this is happenning..
I gave the same experiment to other girl, to do it, to be sure that I am not making the same mistake with solutions, but she has got the same results...

[Borek]

I can not find a logical explanation why this is happenning.

At the same time you refuse to follow the only reasonable advice. You will have to live without an answer.

[always smile]

I did not say that I will not try to do that, I just try to find an answer if it is there any rule for this titration, that I do not know...

[Arkcon]

Its hard to follow your question, and Borek: has given you the best of help possible -- just keep titrating to the endpoint.  Then, if its very far outside of your specifications, try to find out why.  If it is exactly 2 times, then look for that error.  If its exactly 10 times, look for that sort of error.  Try to run some sort of standard, test reaction, to see if there's an instrument fault.