A heap of 200 g of leaf litter decays with a rate k = 0.35 for each year…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
A heap of of leaf litter decays with a rate for each year. (The model is an A-Level and IB idea and is not in the NEET syllabus.)
- What mass is left after years? Use and give the answer to one decimal.
- What is the half-life of the litter, in years? Use and give the answer to two decimals.
Need a reminder? The key ideaShow
The five steps of decomposition are fragmentation, leaching, catabolism, humification and mineralisation. Lignin and chitin slow decomposition. Nitrogen and sugars speed it up. Warmth, moisture and oxygen favour it. A model: , with half-life .
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Given. , for each year, years.
Plan. Use the decay equation, then the half-life formula.
Step 1. (a) . . .
Step 2. (b) years.
Answer: ; years.
Check. After the half-life the litter should be . Two years is a little more than years, so slightly less than is left.
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