Question

A) How many moles of oxygen atoms are in 4.48 moles of magnesium phosphate: Mg₃(PO₄)₂ (Mw. 262.87 g/mol)?

B) How many moles of hydroxide ion are in 4.58 moles of aluminum hydroxide: Al(OH)₃ (Mw. 78.00 g/mol)?

C) How many iron ions are in 4.5 moles of iron (III) carbonate: Fe₂(CO₃)₃ (Mw. 291.73 g/mol)?

Answer 1

1 mole correspond to 6.023*10²³ atoms

1 mole of Mg3(PO4)2 contains 8moles of oxygen atoms

4.48 moles contains 4.48*8=35.84 moles of oxygen atoms

1, mole =6.023*10²³ atoms

35.83 moels of oxygen atoms correspond to 35.84*6.023*10²³ atoms=215.8*10²³ atoms of oxygen

b) there are 3 moles of hydroxide (OH) ion in 1 mole of aluminium hydroxide, Al(OH)3

4.58 moles of Al(OH)3 contains 4.58*3= 13.74 moles of chloride ions

c) 1 mole of Iron (III) carbonate contains 2 moles of iron ion

4.5 moels of Fe2(CO3)3 contains 4.5*2 moles of iron ion= 9 moels of iron ion =9*6.023*1023 ion ions=5.4*10²⁴ iron ions