Dewi Erisa Nainggolan : Kajian Pelapukan Geokimia R C Tanah Andisol Di Desa Tongkoh Kecamatan Tiga Panah Kabupaten Karo, 2007.
USU Repository © 2009
dihitung dua decimal
4. Magnesium MgO
Penetapan Magnesium dalam HCl 25 Bahan-bahan
Larutan Chlorida LaCl
3
20000 ppm Mg Ditimbang 53,5 garam LaCl
3
. 7H
2
O, ditambah 20 ml HCl 25 dan dilarutkan dengan air destilasi di dalam labu ukur 1 liter dan dipenuhkan hingga tanda garis.
Larutan seri standard ; 0-1-2-5-10-20-30 ppm Mg Dipipet 0-1-2-5-10-20-30 ml larutan standard 100 ppm Mg, masing-masing
dimasukkan ke dalam labu ukur 100 ml, ditambah 12,5 ml larutan HCl 25 dipenuhkan hingga tanda garis dengan air destilasi
Alat-alat Atomic Adsorbtion Spectrophotometer
Cara kerja Larutan seri standard 1-30 ppm Mg, larutan blanko dan larutan contoh filtrate
HCl 25 . Masing-masing dipipet ke dalam tabung reaksi, ditambah 1 ml larutan 20.000 ppm La. Larutan contoh dan blanko dipergunakan larutan sisa pengukuran
Kalsium Ca, bersama-sama dengan larutan seri standard. Diukur dan dibaca “absorbance” pada alat AAS.
Perhitungan Dari hasil pengukuran “absorbance” seri standard, dibuat garfik kurva, yang mana
kepekatan larutan seri standard 0-10 ppm sebagai absis dan “absorbance” sebagai ordinat. Kepekatan larutan contoh dibaca pada grafik.
MgO = Mg-garfik x 1001000 x 1,4 x 100 x 100 berat contoh tanah kering 105
C g x 100 dihitung dua decimal
5. Mangan Mn
2
O
3
Penetapan total Mn Bahan-bahan
1. Asam Florida HF 48
2. Asam sulfat H
2
SO
4
18 N 3.
Asam Nitrat HNO
3
4. H
3
PO
4
Dewi Erisa Nainggolan : Kajian Pelapukan Geokimia R C Tanah Andisol Di Desa Tongkoh Kecamatan Tiga Panah Kabupaten Karo, 2007.
USU Repository © 2009
5. KlPO
4
6. Larutan standar 1000 ppm
7. Larutan standar 10 ppm
Prosedur :
1. Place 1 g of soil passing a 100 mesh screen in a platinum
evaporating dish 2.
Add 10 ml of HNO
3
, heat dish slowly 3.
Evepotrate the contents to dryness and ingite the residu in a muffle furnace at 500
C for 30 minutes 4.
Cool the dish 5.
Add 5 ml of 18 N H
2
SO
4
and 10 ml of HF and stir the mixture with platinum strring rod
6. Heat the dish slowly inb fume hood of sand-bath until the H
2
SO
4
has fumed strongly for 30 minutes 7.
Cool the dish 8.
Fill it about ¾ full wuth H
2
O and evaporate the contents to strong fuming of H
2
SO
4
again for 30 minutes 9.
Allow the dish to cool add 10 to 20 ml of H
2
O and place the dish on water bath for 10 minutes
10. Filter the solution into a 100 ml volumetric flash, washing the filter
paper with hot water 11.
Allow the flask to cool, and bring the solution to volume with H
2
O 12.
Transfer an aliquot containing from 0.001-0.3 mg og Mn to a 100 ml beaker and add 2 ml of HNO
3
, 5 ml 0f 85 H
3
PO
4
and about 0.3 g of KIO
4
13. Cover the beaker with a watch caustiously bring the solution to a
boil on a hot plate, and continue to boil the solution gently for at least 5 minutes after the color develops
14. Cool the beaker to room temperature, transfer the solution to a 50
ml volumetric flask and bring with H
2
O. mix the contents of the flask thourghly
15. Measure the light transmittance at 540 m
6. Natrium NaO
