Answer :
Answer:
[tex]\boxed {\boxed {\sf 1.9 \ moles \ Mg}}[/tex]
Explanation:
To convert from grams to moles, the molar mass is used. This tells us the grams in 1 mole of a specific substance. It can be found on the Periodic Table.
- Magnesium (Mg): 24.305 g/mol
Use the molar mass as a ratio.
[tex]\frac { 24.305 \ g \ Mg}{1 \ mol \ Mg}[/tex]
Multiply by the given number of grams.
[tex]45 \ g \ Mg *\frac { 24.305 \ g \ Mg}{1 \ mol \ Mg}[/tex]
Flip the fraction so the grams of magnesium can cancel.
[tex]45 \ g \ Mg *\frac {1 \ mol \ Mg }{24.305 \ g \ Mg}[/tex]
[tex]45 *\frac {1 \ mol \ Mg }{24.305 }[/tex]
[tex]\frac {45 \ mol \ Mg }{24.305 }[/tex]
[tex]1.85147089076 \ mol \ Mg[/tex]
The original measurement of grams has 2 significant figures, so our answer must have the same.
For the number of moles we calculated, that is the tenth place. The 5 in the hundredth place tells us to round the 8 to a 9.
[tex]1.9 \ mol \ Mg[/tex]
45 grams of magnesium is about 1.9 moles.