Question

The presence of iron ions in drinking water can cause discoloration of the water, a change in taste, darkening of prepared foods, and, in some cases health problems. A slow and uniform precipitation of iron, as Fe(OH), can be used as a gravimetric analysis technique. This can be facilitated when the precipitating OH is generated within the solution using urea decomposition: H2NCONH2 + H20 CO2 + 2 NH3 The NH3 generated converts to OH via this reaction: H2O + NH, NH4+ + OH- (a) A solution containing 1.80 x 10 M Fe3+ is treated with urea to precipitate the Fe3as Fe(OH). What molarity of urea is needed to precipitate the iron if a 25% excess of urea is desired? Solution: Murea (b) The Fe(OH)produced by the process described above is gelatinous so is ignited to convert it to Fe2O3. What is the percent of iron in a solution if 100.0 grams of the solution yielded, upon proper treatment, 7.15 grams of Fe2O3? Note first determine the gravimetric factor for this precipitation. Solution: Gravimetric factor = Mass percent Fe =

Answer 1

Answa Deactfon is PrOm the arven HoNcONH+HoCataNHg The neaclton: Haot NHs Gennated Conved to 0tr via ths NHATOH a solution containi na8ox 16 MFes a) Here taeated with 40 fest as precipitade the Unea Felork ie, contendiation of wea could be. I0 100 ouro) +[oxoH XIO we 9.05x10 2M

Tiven the pecendage of taon in a galudion 64 f00.0 tho olulfon yeild ad uPon Padp dheadment t-15 guams of Feos The finsd detumine e gavimohe factor fon this paecipidadfon hene festt30H felots-i) 2 fecotls Holan man of Pego3 159.69 9m A nd the fetot) fe203 +3 0i = (o 6.869/mol 55.8409 mo/ fegt Molas man 1e hne pesos laimetnic facton 1 mol fesos Iq.699pe03 55.8u5e i molfe &molfe X 0.6१৭ ५ १e Hue the in t.s9 ams 03 twas 00 9am man of fe: 50001 amg Hlence Solveg