A. The chemical formula for iron (III) sulfate is Fe2(SO4)3. How many atoms of each element are present? 2 iron, 3 sulfur, 12 oxygen
3 iron, 3 sulfur, 12 oxygen
2 iron, 1 sulfur, 4 oxygen
6 iron, 3 sulfur, 12 oxygen
B. How many moles of hydrogen are in 1.8 mole(s) of quinine?

Express your answer using two significant figures.

C. How many moles of carbon are in 5.4 moles of quinine?

Express your answer using two significant figures.

D. How many moles of nitrogen are in 2.0×10−2 mole of quinine?

Express your answer using two significant figures.

A. 2 Fe, 3 S and 12 O

B. 43 moles of H

C. 1.0×10² moles of C

Explanation:

A. Formula for iron (III) sulfate is Fe₂(SO₄)₃

This salt has 2 atoms of iron and 3 sulfates, so in total we have:

2 Fe, 3 S and 12 O

Pay attention to the subscripts

B. Formula for quinine is: C₂₀H₂₄N₂O₂

If we continue with the example before we can say that 1 mol of Iron (III) sulfate contains 2 moles of Fe, 3 moles of S and 12 moles of O

Then, 1 mol of quinine contains 24 moles of H

So 1.8 moles of quinine, may contain (1.8 . 24) /1 = 43 moles of H

C.  1 mol of quinine contains 20 moles of C

5.4 moles of quinine may contain (5.4 . 20) /1 = 1.0×10²

(As the answer must be in 2 significant figures and the real answer is 108, I had to use scientific notation)

un recipient conține 6,4 moli de gaz. gazul hidrogen reprezintă 25% din totalul kilometrilor din container. în cazul în care presiunea totală este de 1.24 atm ceea ce este