To determine whether 0.5 mole of Mg atoms and 0.5 mole of oxygen gas have the same mass, we need to compare the molar masses of magnesium and oxygen.
The molar mass of an element or compound is the mass of one mole of that substance. It is calculated by summing up the atomic masses of all the atoms in the formula.
The molar mass of magnesium (Mg) is approximately 24.31 grams per mole, while the molar mass of oxygen (O2) is approximately 32.00 grams per mole.
Now, let's calculate the mass of 0.5 mole of each substance:
Mass of 0.5 mole of Mg atoms: Mass = 0.5 mole × molar mass of Mg Mass = 0.5 mole × 24.31 g/mol Mass = 12.155 grams
Mass of 0.5 mole of oxygen gas (O2): Mass = 0.5 mole × molar mass of O2 Mass = 0.5 mole × 32.00 g/mol Mass = 16.00 grams
Therefore, 0.5 mole of Mg atoms and 0.5 mole of oxygen gas do not have the same mass. 0.5 mole of Mg atoms has a mass of 12.155 grams, while 0.5 mole of oxygen gas has a mass of 16.00 grams.