Distillation of a mixture
Hi, you've asked an incomplete question. However, I assumed you are referring to the article found on the Scientific American website.
Explanation:
<em>Remember,</em> according to that article we are told that scientists notice that these insects have a long nymphal (immature form before becoming adults) stage, one that can last up to 13 to 17 years on the ground before they leave the ground looking for mating partners.
Because it is only after mating occurs at this point that their eggs are laid, that is why scientists believe that cicadas only reproduce every 13 or 17 years.
Answer:
3.02 X1023 atoms Ag limol. - - 0.50 1 moles. 6.02241023 atoms.
Answer:
23.34 %.
Explanation:
- The percentage of water must be calculated as a mass percent.
- We need to find the mass of water, and the total mass in one mole of the compound. For that we need to use the atomic masses of each element and take in consideration the number of atoms of each element in the formula unit.
- <em>Atomic masses of the elements:</em>
Cd: 112.411 g/mol, N: 14.0067 g/mol, O: 15.999 g/mol, and H: 1.008 g/mol.
- <em>Mass of the formula unit:</em>
Cd(NO₃)₂•4H₂O
mass of the formula unit = (At. mass of Cd) + 2(At. mass of N) + 10(At. mass of O) + 8(At. mass of H) = (112.411 g/mol) + 2(14.0067 g/mol) + 10(15.999 g/mol) + 8(1.008 g/mol) = 308.5 g/mol.
- <em> Mass of water in the formula unit:</em>
<em>mass of water</em> = (4 × 2 × 1.008 g/mol) + (4 × 15.999 g/mol) = 72.0 g/mol.
- <em>So, the percent of water in the compound = [mass of water / mass of the formula unit] × 100 = [(72.0 g/mol)/(308.5 g/mol)] × 100 = 23.34 %</em>
