How many moles are in 45.0 sample of #MgO#?
1.12 moles MgO
Mass of one mole of Magnesium Oxide is 40.3044 g
We can set up conversion factors/ ratios
1 mol MgO = 40.304 g of MgO
1 mol MgO / 40.304 g MgO (a) or 40.340 g MgO / 1 mol MgO (b)
Using the conversion factor (b) we can find number of moles.
45.0 g MgO x ( 1 mol MgO / 40.304 g MgO )
1.1 2 moles MgO