Question

Phosphorus reacts with oxygen to form diphosphorus pentoxide, P,O. 4P(8) +502(8) 2P,0,() How many grams of P,0, are formed when 6.95g of phosphorus reacts with excess oxygen? Show the unit analysis used for the calculation by placing the correct components into the unit-factor slots. 696 5Px (+ 6.95 PX ) ( ) ( ) ( «P,0, Answer Bank 141.94 g P,0 30.97gP 1 mol P,0, 1 mol P 5 mol 0, 1 molo, 32.0050, 2 mol P,0, mol P

Answer 1

Molecular mass of P = 31 g/mol Molecular mass of P2O5 = 284 g/mol 4P + 502 → 2 P205 Standard Mass 4x31g 2x284 124g 568g Given Mass 6.95 g From above data, it can be observed that, 124 g of P produces = 568 g of P205 1 g of P produces = (568/124) g of P2O5 6.95 g g of P produces = 6.95 x (568/124) g = 31.84 g of P205 (2) Mass of NH4Br = 3.166 g Molar mass of NH4Br = 98 g/mol Number of moles = Mass / Molar mass Number of moles NH4Br = 3.166/98 = 0.0323 moles Now, I mole contains = 6.022 x 10–23 molecules So, 0.0323 moles of NH4Br =0.0323 x 6.022 x 1023 molecules of NH4Br = 1.94 x 1022 molecules of NH4Br