A plant is fed 60 kg of fresh dung each day, mixed with 60 L of water…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
A plant is fed kg of fresh dung each day, mixed with L of water. Take each kg of dung as L of slurry. The slurry stays in the tank for days.
- How many litres of slurry are fed each day?
- What volume must the digester have, in cubic metres?
- A sample of g of glucose is changed to methane and carbon dioxide by . The molar mass of glucose is g per mol. What volume of methane is made, at and atm, where mol fills L?
Need a reminder? The key ideaShow
Methanogens such as Methanobacterium make methane without oxygen. Biogas is mostly methane. Methane gives MJ for each m³ and LPG gives MJ for each kg. The digester volume is the slurry fed each day times the days that it stays in the tank. The reaction gives mol of methane from mol of glucose, and mol of gas fills L at and atm.
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. Dung: kg a day, taken as L. Water: L a day. Time in the tank: days. Glucose: g.
Plan. Add the dung and the water, multiply by the days, and then use the equation.
Step 1. The slurry. L each day.
Step 2. The digester. L, which is m³.
Step 3. The glucose. mol. The equation gives mol of methane for each mole of glucose, so the methane is mol.
Step 4. The volume. L of methane.
Answer: L; m³; L.
Check. Half of the gas is methane and half is carbon dioxide, so the biogas from this glucose is L, of which L is methane.
Watch out. The glucose equation gives the most that could be made. Real wastes make less, and they hold more than sugar.
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