Question

As part of a soil analysis on a plot of land, a scientist wants to determine the ammonium content using gravimetric analysis with sodium tetraphenylborate, Na*B(C,H,7. Unfortunately, the amount of potassium, which also precipitates with sodium tetraphenylborate, is non-negligible and must be accounted for in the analysis. Assume that all potassium in the soil is present as K2CO3 and all ammonium is present as NH4CI A 5.075 g soil sample was dissolved to give 0.500 L of solution. A 100.0 mL aliquot was acidified and excess sodium tetraphenylborate was added to precipitate both K and NH ions completely Compound KB(C H54 Formula mass 358.33 g/mol 337.27 g/mol K,CO, 138.21 g/mol The resulting precipitate amounted to 0.251 g. A new 200.0 mL aliquot of the NH,CI 4 53.492 g/mol original solution was made alkaline and heated to remove all of the NH as NH,. The resulting solution was then acidified, and excess sodium tetraphenylborate was added to give 0.149 g The resulting precipitate amounted to 0.251 g. A new 200.0 mL aliquot of theCO 138.21 g/mol NHC53.492 g/mol original solution was made alkaline and heated to remove all of the NH as NH3. The resulting solution was then acidified, and excess sodium tetraphenylborate was added to give 0.149 g of precipitate Find the mass percentages of NH,Cl and K2CO in the original solid. mass percentage of NH,Cl mass percentage of K2CO:

Answer 1

Comment in case of any doubt.

= 0.149 a 00 m = 0.149 So, rmans