Answer:
[tex]\boxed {\boxed {\sf 2.61 \ mol \ O}}[/tex]
Explanation:
To convert from grams to moles, the molar mass is used. This number tells us the grams per mole of a substance. It can be found on the Periodic Table. Look for oxygen.
Use this number as a ratio.
[tex]\frac {15.999 \ g \ O }{ 1 \ mol \ O }[/tex]
Multiply by the given number of moles.
[tex]41.8 \ g \ O *\frac {15.999 \ g \ O }{ 1 \ mol \ O }[/tex]
Flip the fraction so the grams of oxygen cancel.
[tex]41.8 \ g \ O *\frac { 1 \ mol \ O }{ 15.999 \ g \ O}[/tex]
[tex]41.8 *\frac { 1 \ mol \ O }{ 15.999 }[/tex]
[tex]\frac { 41.8 \ mol \ O }{ 15.999 }= 2.61266329146 \ mol \ O[/tex]
The original measurement of grams has 3 significant figures (4, 1, and 8). Our answer must have the same. For the number we calculated, that is the hundredth place. The 2 in the thousandth place tells us to leave the 1.
[tex]2.61 \ mol \ O[/tex]
41.8 grams of O has 2.61 moles of oxygen.
