To solve this problem, you can follow these steps:
Step 1: Calculate the mass of oxygen that was removed.
To find the mass of oxygen, subtract the mass of the metal left over from the initial mass of the compound.
Mass of oxygen = Initial mass of compound - Mass of metal left over
Mass of oxygen = 39.46 g - 31.70 g
Mass of oxygen = 7.76 g
Step 2: Convert the mass of oxygen to moles.
To do this, divide the mass of oxygen by its atomic mass.
Number of moles of oxygen = Mass of oxygen / Atomic mass of oxygen
Number of moles of oxygen = 7.76 g / 16.00 g/mol
Number of moles of oxygen = 0.485 mol
Step 3: Determine the number of moles of metal present.
The number of moles of the metal is equal to the number of moles of oxygen because the formula for the metal oxide is MO, indicating a 1:1 ratio of metal to oxygen.
Number of moles of metal = Number of moles of oxygen
Step 4: Calculate the molar mass of the metal.
To find the molar mass of the metal, divide the mass of the metal by the number of moles.
Molar mass of metal = Mass of metal / Number of moles of metal
Molar mass of metal = 31.70 g / 0.485 mol
Molar mass of metal ≈ 65.4 g/mol
Step 5: Identify the element.
The molar mass of the metal is approximately 65.4 g/mol. By referring to the periodic table, you can determine which element has a molar mass close to this value. In this case, the element with the closest molar mass is Zinc (Zn), which has a molar mass of 65.38 g/mol.
Therefore, the atomic mass of M is 65.4 amu, and the element is Zinc (Zn).