3. if 48 g of magnesium reacts with oxygen gas, how many grams of magnesium oxide will be formed according…

Explanation:

Step1: Calculate moles of Mg

The molar mass of Mg is approximately 24 g/mol. Using the formula $n=\frac{m}{M}$, where $n$ is the number of moles, $m$ is the mass, and $M$ is the molar mass. For Mg, $m = 48$ g and $M=24$ g/mol. So $n_{Mg}=\frac{48\ g}{24\ g/mol}=2$ mol.

Step2: Determine mole - ratio

From the balanced chemical equation $2Mg + O_2\rightarrow2MgO$, the mole - ratio of Mg to MgO is 2:2 or 1:1. So the number of moles of MgO formed is equal to the number of moles of Mg that react. Thus, $n_{MgO}=n_{Mg} = 2$ mol.

Step3: Calculate mass of MgO

The molar mass of MgO is $M_{MgO}=24\ g/mol + 16\ g/mol=40$ g/mol. Using the formula $m = n\times M$, for MgO, $n = 2$ mol and $M = 40$ g/mol. So $m_{MgO}=2\ mol\times40\ g/mol = 80$ g.

Answer:

80 g