accuracy in sulfate % fertiliser prac (1 Viewer)

[Soul Searcher]

i have a few steps to analyse; i need to find out how these particular steps increases accuaracy. I've tried, but it's difficult.

step 1)
weight out 1.0g of fertiliser onto a piece of weighing paper and then transfer to a 250ml beaker. add 25ml of de-ionised water to dissolve. to this solution add 10 drops of conc. HCl <-- does anyone know why HCl is even added?

all i got for that step was...nothing

step 4)
add the hot barium nitrate solution very slowly with constant stirring to the hot fertiliser solution.

for this step i know that slow = steady = no spills etc
and that constant stirring = uniform spreading of particles? ... which i don't know how it would add to accuracy....or possibly provoking complete precipitation? mmm

 

[xiao1985]

1) to further dissolve any undissolved precipitates.

4) to ensure proper mixing of barium nitrate with the soln

 

[pennyjurd]

why do we have to heat the barium nitrate anyway?

 

[xiao1985]

to avoid things from ppt'ing

 

[lunavixen]

if i could help you i seriously would, my prac ended up creating matter (not that it's possible)

 

[mcs-one]

i have a few steps to analyse; i need to find out how these particular steps increases accuaracy. I've tried, but it's difficult.

step 1)
weight out 1.0g of fertiliser onto a piece of weighing paper and then transfer to a 250ml beaker. add 25ml of de-ionised water to dissolve. to this solution add 10 drops of conc. HCl <-- does anyone know why HCl is even added?

all i got for that step was...nothing

step 4)
add the hot barium nitrate solution very slowly with constant stirring to the hot fertiliser solution.

for this step i know that slow = steady = no spills etc
and that constant stirring = uniform spreading of particles? ... which i don't know how it would add to accuracy....or possibly provoking complete precipitation? mmm

HCl reduces co-precipitation.

when u do experiment u normally get around 5% when in fact the value shud be 70%. so correct produces shud increase accuracy. use multiple filtration paper, make sure there snt any co-precipitation.

 

[Undermyskin]

We 'evacuated' to increase the speed of filtration!

The prob with this prac is normally involved the filtration step. The tiny particles can easily get through the holes of filter papers. (ARGHHH) Although it is said that heating then letting the solution slowly cool down can make the precipitate particles formed bigger, I still can't make it work.

 

[yorkstanham]

hcl is added to precipitate out any lead and to get rid of any carbonates in the fertiliser.

filter paper shouldnt really be used because the ba2so4 particles can get through it, you should use a sintered glass filter

 

[Darrow]

Omg,
Hello York!
Anycase,
Sintered glass filters or Ashless filter paper, which you burn out in the crucible
Both work