A person excretes 26 g of urea in a day…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
A person excretes g of urea in a day.
- How many grams of nitrogen are in this urea?
- How many grams of ammonia would carry the same nitrogen?
- How many grams of uric acid would carry the same nitrogen?
Need a reminder? The key ideaShow
The three nitrogenous wastes are ammonia (one nitrogen atom in a molecule), urea (two) and uric acid (four). Ammonia is the most toxic and needs the most water. Uric acid is the least toxic and leaves as a paste. Ammonotelic animals are bony fishes, aquatic amphibians and aquatic insects. Ureotelic animals are mammals, many terrestrial amphibians and marine fishes. Uricotelic animals are reptiles, birds, land snails and insects. Use u, ammonia u, urea u and uric acid u.
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. Urea: g. Masses in u: N , ammonia , urea , uric acid .
Plan. Find the nitrogen in the urea. Then find the mass of another waste that holds the same nitrogen.
Step 1. Nitrogen. A urea molecule holds u of nitrogen in u. So g.
Step 2. Ammonia. An ammonia molecule holds u of nitrogen in u. The mass is g.
Step 3. Uric acid. A uric acid molecule holds u of nitrogen in u. The mass is g.
Answer: g of nitrogen; g of ammonia; g of uric acid.
Check. The more nitrogen atoms a molecule holds, the more of that waste is needed to hold the same nitrogen, because each molecule is heavier.
Watch out. Do not forget that urea has two nitrogen atoms. Using one atom gives half the right answer.
Discussion (0)
Log in to join the discussion.
Loading…