My original sample of mixed salt had a mass of 8.9 grams. After heating the mixture in the crucible and weighing it multiple times my final mass of salt ended up being 4.9. How many moles of oxygen were driven off?

Lost on how to do this been a while since I have done this.

Assuming the only ingredients could be decomposed to give oxygen (and nothing else) then oxygen driven off must have been 8.9-4.9 = ? Then mol = grams/molar mass.

To find the number of moles of oxygen that were driven off during the heating process, you need to first determine the change in the mass of the salt mixture.

Change in mass = Initial mass - Final mass
Change in mass = 8.9 g - 4.9 g
Change in mass = 4.0 g

This 4.0 g represents the mass lost during the heating process, which is due to the loss of oxygen.

Next, you need to convert the mass of the oxygen lost to moles using the molar mass of oxygen. The molar mass of oxygen (O) is approximately 16.00 g/mol.

Number of moles of oxygen = Change in mass / Molar mass of oxygen
Number of moles of oxygen = 4.0 g / 16.00 g/mol
Number of moles of oxygen = 0.25 mol

Therefore, approximately 0.25 moles of oxygen were driven off during the heating process.