Question

practice problems for analytical chemistry

b) 0.00746M ROH C) 0.40M HCIO (pK=6.67) Question 2. If you have a 0.0030M solution of Li+(Ksp LiF= 1.7x10%), a 0.0040M of Th (Ksp The = 2.9x10-29), and a 0.0030M of Sr (Ksp Sr+;= 2.9x10%), and you use NaF (aq) to separate them by precipitation a) Can you remove 99.99% of the thallium before precipitating Li? b) When Strontium begins to precipitate, what are the Lithium and Thallium Concentrations? Ouestion 3. Given: K = 5.6x 10-14 for the following aqueous equilibrium, suppose sample A is

Answer 1

for Kipe that in st 4:1 182 m e r The concentration of frion needed 41 x 10 m They & That 45 S 45 Ksp = [s] [3] S- & Ksp = 82.9x1029 = 1.96x 100M The concentression of f ion neededs 4x196x15 m For = 7 84156m Sre 25+ 2F ksp= Esrat [F-32 s sygn s3 = ks = 2.9x109 S = 32,98169 = 1.426x 103 min 25

lon needed The Concentration of a * 4x4 - 2x1.426x153 m 2.85*15m Since the concentration of f low needes for the precipitation of the is in 101 order and less than lower about 10 times than the concentration needed for precipitation of Lif therefore sauga The precipitation before preustrations

# Sr began to precipitare at Co-3= 2:85x153m abou This value is 103 times higher than the frion needed for Precipitation of the trium. Therefore the concentration of thorrium is almost zero. This value off of 2-85x 10 m is o times lower than the concentration needed for Precipitation of Lithium. There fort. Therefore When Sy began to precipitate concentration of thorrium is zero and Lithium is 0.003m