Question

How many grams of oxygen are contained in a sample of H₂O that also contains 3.85 moles of hydrogen atoms?​

Answer 1

30.8 grams O

Step-by-step explanation:

In H₂O, there are 2 moles of hydrogen for every 1 moles of oxygen. You can use this to convert between moles of H and moles of O. Then, you can use the molecular weight of oxygen (15.998 g/mol) to convert between moles O and grams. The answer should have 3 sig figs because the given value (3.85) also has 3 sig figs.

3.85 moles H 1 mole O 15.998 g
-------------------- x ------------------ x -------------------- = 30.8 grams O
2 moles H 1 mole O