Question

1. What is the mass of 0.25 moles of Na.O? 2- How many moles are in 10000 miligram of Fels? 3. How many atoms are in 0.25 moles of MgFz? 4. Find the mass of 100000 atom of KOH. 5. How many molecules are in 5 moles of Mgiz? 6- Find % of all in 1 mole of Al(OH)3. 7- How many gram of Oxygen is in 22 gram of Al(OH)3 22g x 100 8. How many atoms are in 25 gram of Al(OH)3.

Answer 1

ANSWER 1: MW of Na,O=61.9789 So, 1 mole of Na,O=61.9789 g Then, 0.25 moles of Na,O=61.9789 x 0.25 g = 15.4947 g = 15.495 g ANSWER 2: MW of Felz = 436.56 So, 436.56 g of Felz = 1 mole of Felz Then, 1 g of Fel3 = 1/436.56 mole of Felz Therefore, 1000 mg of Fel3 = 1/436.56 mole of Felz Or, 10000 mg of Fel3 = 10/436.56 mole of Fel: = 0.0229 mole of Felz ANSWER 3: 1 mole of MgF2 = 6.023 x 1029 molecule of MgF Now, 1 molecule of MgF, contains one Mg atom and two F atoms Rather, 1 molecule of MgF2 contains three atoms So, 1 mole of MgF2 = 3 x 6.023 x 1023 atoms Or. 0.25 mole of MgF2 = 0.25 x 3 x 6.023 x 1023 atoms = 4.517 x 1023 atoms