Question

please help me with the second column.

Lab Data Sheet 1. Mass of lid (9) Trial 1 6.66904 39.65269 40.29104 Trial 2 16.4783 38.0139 32.54279 2. Mass of crucible and lid (9) 3. Mass of crucible, lid, and magnesium(g) 4. Mass of crucible, lid and compound 1st mass measurement (g) 40.77679 90.47004 38.8188 38.81319 2nd mass measurement (g) 3rd mass measurement (9) CALCULATIONS Trial 2 5383 Trial .89559 •0368 1.1644 1. Mass of Magnesium (9) 2. Moles of Magnesium (mol) 3. Mass of compound (g) 4. Mass of Oxygen in compound (9) 5. Moles of Oxygen in compound (mol) 6. Mole ratio of Magnesium to Oxygen 7. Empirical formula of compound 016575 2.220 me o 8. % by mass magnesium in compound 9. % by mass oxygen in compound 23% 49

Answer 1

So We are dealing with Trial 2

Mass of lid(g)	16.4783	Justification or formula
Mass of crucible and lid(g)	38.0039
Mass of crucible, lid, and Magnesium(g)	38.5422
Mass of crucible lid and compound_1st reading (g)	38.8118
Mass of crucible lid and compound_2nd reading (g)	38.8131
Mass of crucible lid and compound_ average of two reading (g)	=(38.8118+38.8131)/2 = 38.81245
Mass of magnesium(g)	0.5383	=( Mass of crucible, lid, and Magnesium- Mass of crucible and lid) =(38.5422-38.0039)
Moles of Magnesium(mol)	0.02215	= mass of magnesium in g / molecular weight of magnesium in g Molecular weight of magnesium = 24.305 so moles of magnesium = 0.5383/24.305 =
Mass of compound(g)	0.80855	=( Mass of crucible lid and compound_ average- Mass of crucible and lid) =(38.81245-38.0039 =0.80855
Mass of oxygen in compound(g)	0.27025	=(mass of compound-mass of magnesium) = 0.80855-0.5383 = 0.27025
Moles of oxygen in compound(mol)	0.00844558	= mass of oxygen in g/ molecular weight of oxygen in g =0.27025/ 31.999 31.999 is molecular weight of oxygen(O2). = 0.00844558
Mole ratio of magnesium to oxygen	2.6227	= moles of magnesium/moles of oxygen =0.02215/ 0.00844558 = 2.6227
% mass of magnesium in compound	66.58	=(Weight of magnesium/compound mass) x100 =(0.5383/0.80855) x100 = 66.58
% mass oxygen in compound	33.42	=(Weight of oxygen/compound mass) x100 =(0.27025/0.80855) x100 =33.42