The chemical oxygen demand calculator works out chemical oxygen demand (cod) from the values you supply. Enter normality of fas (n), fas for blank (a), fas for sample (b), volume of sample, and the calculator applies the standard relationship straight away, so you get the answer without working through the algebra yourself.
What Is the Chemical Oxygen Demand Calculator?
It is built around chemical oxygen demand (cod), and it works the same way whether you are checking a homework answer, confirming a colleague's figure, or working something out for yourself. Everything runs in your browser, so nothing you enter is uploaded anywhere.
How the Chemical Oxygen Demand Calculation Works
The steps are applied in order, so an output that depends on another output updates as soon as the underlying figures change.
The relationship between normality of fas (n), fas for blank (a), fas for sample (b), volume of sample and chemical oxygen demand (cod) is fixed, so the same figures always give the same answer. That makes it a good cross-check: run the numbers a second way and see whether the result agrees.
Getting a Result You Can Trust
Start with a set of figures you are confident about. If one of the normality of fas (n) or fas for blank (a) or fas for sample (b) or volume of sample values looks wrong, the result will be wrong too, because everything downstream is built on top of it. Work through the outputs one at a time and check that each one is the size you would expect before relying on the last figure.
Frequently Asked Questions
What do I need to work out chemical oxygen demand (cod)?
Enter normality of fas (n), fas for blank (a), fas for sample (b), volume of sample. The calculator then works through the relationship and reports chemical oxygen demand (cod).
What does the chemical oxygen demand actually calculate?
It takes normality of fas (n) and fas for blank (a) and fas for sample (b) and volume of sample and converts them into chemical oxygen demand (cod) using the standard relationship for this problem. Each step is applied in turn, so every output is traceable back to the numbers you typed in.
How should I enter normality of fas (n)?
Use the value you actually have, in the unit shown next to the field. Enter every value in the same unit system. The calculator assumes the figures you supply are consistent, so it cannot correct a mistake that happens before the calculation starts.
Why does a small change in one value move the answer so much?
That happens when an output depends on a ratio, because dividing by a small number magnifies any change in it. Check the units first, then check whether the value you entered is in the range the relationship was designed for.
Can I use this for a quick estimate as well as a precise answer?
Yes. The calculator is built for quick checks, so round your inputs to a sensible number of significant figures and the result will be just as useful. If you need more precision, keep the same method and add digits to the inputs rather than adjusting the method itself.