Question

convert 1.00 g of each element to moles. how many moles of magnesium are in 1.00 g? 1.00 g mg = how many moles of manganese are in 1.00 g? 1.00 g mn = how many moles of helium are in 1.00 g? 1.00 g he =

Explanation:

Step1: Recall molar - mass formula

The formula to convert mass ($m$) to moles ($n$) is $n=\frac{m}{M}$, where $M$ is the molar mass of the element.

Step2: Find molar mass of magnesium

The molar mass of magnesium ($Mg$) is $M_{Mg}=24.31\ g/mol$. Then, for $m = 1.00\ g$ of $Mg$, $n_{Mg}=\frac{1.00\ g}{24.31\ g/mol}\approx0.0411\ mol$.

Step3: Find molar mass of manganese

The molar mass of manganese ($Mn$) is $M_{Mn}=54.94\ g/mol$. Then, for $m = 1.00\ g$ of $Mn$, $n_{Mn}=\frac{1.00\ g}{54.94\ g/mol}\approx0.0182\ mol$.

Step4: Find molar mass of helium

The molar mass of helium ($He$) is $M_{He}=4.003\ g/mol$. Then, for $m = 1.00\ g$ of $He$, $n_{He}=\frac{1.00\ g}{4.003\ g/mol}\approx0.2498\ mol$.

Answer:

$1.00\ g\ Mg\approx0.0411\ mol$
$1.00\ g\ Mn\approx0.0182\ mol$
$1.00\ g\ He\approx0.2498\ mol$