garage chemist - 1-12-2004 at 14:18
I've got some problems in calculating the nitrogen content of NC.
The cotton (boiled for 1h in 4% NaOH to remove resins, then washed + dried) weighed 3,1g before the nitration.
After the nitration (11ml 95% HNO3, 20ml 96% H2SO4, standing overnight at ca. 5°C), it weighed 5,2g (after washing + drying).
The weight difference is 2,1g, this is the weight of the added nitrate groups (-NO2, the third "O" was already in place at the hydroxyl
groups).
Those 2,1g represent about 40% of the 5,2g of NC, that means 40% of the weight of the NC are -NO2 groups (attached to the "O" from the
former -OH group).
Now, how do I calculate the nitrogen content from this?
Blind Angel - 1-12-2004 at 16:50
40% imply that you got a 100% reaction with no loss which would be very improbable. Calculate how much mole you had of coton, then calculate how much
mole you had from NC. Once you have the number of mole of NC just calculate how much of it is given by N
(C<sub>x</sub>H<sub>z</sub>O<sub>y</sub>N<sub>w</sub>, w*MM<sub>N</sub>=amount given by N)
then do a percentage ((amount given by N/M<sub>NC</sub>
=%) Multiply
your final mass by this number and you'll have the mass given by the N