Question

(3) 3. How many grams of oxygen are present in a sample containing 5.75 x 1021 formula units of manganese (II) phosphate ? (6) 4. Determine the percent composition (by mass) for each element in ammonium dichromate, (NH4)2Cr2O7.

Answer 1

Q 3.

Answer 1.2224 gram oxygen

Q4.

Answer :

For Nitrogen 11.11 %

For Hydrogen 3.1746 %

For Chromium 41.2698 %

For Oxygen 44.44 %

Details answer given in the attachment...

Now we required onggen in gram. so molar mass of oxygen = 16 g/mol mass of oxygen = 7.64x10 mod x 16 g/mol mass of oxygen = 1.2224 g So mass of oxygen = 1-224 g Answer d.4) Determine the percent composition (by mass) for each element in Ammonium dichromate , (NH4)2CR2O7 Answer : Elements of (NH4)₂CR2O7 N OS H Go Nitrogen Hydrogen Cromium a 8 a atom atom atom o onggen 7 atom of from periodic Table get molar mass Now we each element

Total mass of NH) Cr2O7 = 2529 So mass us of Hydrogen Ans %. -X100 % - 3.1746 252 Cromium no. of mass of cr atom= 2 I co atom= 52 g So for a co atom = 52x2 = 104 g total mass of NH4)₂CR2O2 = 252 g mass % of Heydbolden Cromium so Ang 104 .x100 % = 41. 2698 % 252 4) 0 (oxygen) no. of o atom=7 mass of t o atom= 169 for 7 atom = 16x7= 112 g Total mass of (INS) ₂082 07 = 252g so mass so of Oxygen 112 x 100 %. = 44.44 %. Ans - 252