Hi guys, it’s day 2 of my attachment and the objective for today was to determine the organic carbon content in soil. We’ll be using 2 reagents for this so we started with preparing the reagents.

Preparing 2000ml K₂Cr₂O₇

We rinsed the volumetric flasks we’ll be using in preparing the reagents with distilled water before we started.

_{Rinsing volumetric flask with distilled water before use}

To prepare 1000ml K₂Cr₂O₇, we weigh 49.04g of K₂Cr₂O₇. Since we will be preparing 2,000ml, we weighed twice this amount which is 98.08g.

_{Weighing 98.08g of K2Cr2O7}

We added distilled water to our 98.08g K₂Cr₂O₇. Then We placed the solution on a magnetic stirrer to aid dissolution and uniform solution.

_{Adding distilled water to dissolve K2Cr2O7 salt}

_{Stirring solution using magnetic stirrer to aid dissolution of K2Cr2O7 salt}

After it completely dissolved, we poured it into our 2000ml volumetric flask and added more distilled water to reach the 2000ml mark and we closed with a cork. Our potassiumdichromate reagent is ready!!

_{Dissolved K2Cr2O7 poured into 2000ml volumetric flask}

Preparing 1000ml FeSO₄

We weighed 139.0g of FeSO₄ into a beaker, added distilled water and placed on a magnetic stirrer to aid dissolution.

_{Weighing 139g of FeSO4}

_{Distilled water added to FeSO4 salt and placed on magnetic stirrer to dissolve}

After the FeSO₄ salt was completely dissolved, we added 20ml H₂SO₄, and we poured it into a 1000ml volumetric flask and added more distilled water to reach the 1000ml mark, and we corked the flask. Simple. We prepared our FeSO₄ reagent and now it’s time to start the experiment itself.

_{Distilled water added to dissolved FeSO4 salt solution to reach 1000ml mark of volumetric flask}

Determining Organic Carbon Amount in Soil Sample

We weighed 1g of of organic matter into one conical flask and 0.5g of soil and organic matter into 5 other conical flasks. Then we measured 10ml K₂Cr₂O₇ into the soil samples and organic matter.

_{10ml K2Cr2O7 added to 1g of organic matter and 0.5g of each of the 4 separate samples}

We then added 20ml H₂SO₄ in a fumehood. The solution was hot upon adding H₂SO₄, so we allowed the solutions cool down in the fumehood.

_{Adding 20ml H2SO4 in fume hood}

_{Samples cooling in fume hood}
From the fumehood, we added 10ml distilled water and 5ml ortho-phosphoric acid. Then we poured the FeSO₄ into the burette and titrated it against the soil and organic matter sample containing excess K₂Cr₂O₇ so that the remaining K₂Cr₂O₇ can be determined, subtracted from the total K₂Cr₂O₇ volume, and used to calculate the organic carbon available in the soil sample.

_{Titrating FeSO4 against K2Cr2O7}

In titrating, we titrated the FeSO₄ against soil and organic matter sample containing excess K₂Cr₂O₇, with our end point showing a a green color of iron in Ferric Sulphate.

Below is our table of results

SN	Lab No	Initial/V	Final/V	Titre	Weight(g)
BLK	B11	0.00	30.90	30.90
1	507/21	0.00	26.80	26.80	0.1
2	508/21	0.00	22.80	22.80	0.5
3	509/21	0.00	18.00	18.00	0.5
4	510/21	0.00	14.00	14.00	0.5
5	511/21	0.00	6.60	6.60	0.5

The small values of sample 511/21 was due to shortage of K₂Cr₂O₇ and H₂SO₄ so we used 5ml K₂Cr₂O₇ and 10ml H₂SO₄

That was pretty much it for today. Thanks for reading and have a nice day