a 2 ml sample was taken of a saturated solution of barium iodate at 10 degrees C

Question

a 2 ml sample was taken of a saturated solution of barium iodate at 10 degrees C. The sample was mixed with 2 ml of 0.5 M KI and 2 ml of 1 M HCl. the transmittance of the mixture was read and compared to a calibration curve which indicated a concentration of I3- as 5.52*10-4 M calculate the following.

a. the moles of I3- in the mixture.

b. the moles of IO3- in the original sample.

c. the concentration in moles/L of IO3- in the original sample.

d. the concentration of Ba2+ (in M) in the original sample.

e.the Ksp of barium iodate.

Explanation / Answer

a 2 ml sample was taken of a saturated solution of barium iodate at 10 degrees C. The sample was mixed with 2 ml of 0.5 M KI and 2 ml of 1 M HCl. the transmittance of the mixture was read and compared to a calibration curve which indicated a concentration of I3- as 5.53*10-4 M calculate the following. a. the moles of IO3- in the mixture. b. the moles of IO3- in the original sample. c. the concentration in moles/L of IO3- in the original sample. d. the concentration of Ba2+ (in M) in the original sample. e.the Ksp of barium iodate.

ANS:

Volume of Barium iodate=2mL

KI=2mL, 0.5M

HCl=2mL, 1M

Total volume=6mL

[IO3-] = 5.53*10-4 M (from Transmittance)

a)moles of IO3- in mixture=5.53*10-4moles/L*0.006L=3.318E-6moles

b)moles of IO3- in mixture=moles of IO3- in original sample=3.318E-6moles

c. the concentration in moles/L of IO3- in the original sample=

(moles of IO3- in original sample)/Volume of Original sample=

(3.318E-6moles)/0.001L=0.00331M

d. the concentration of Ba2+ (in M) in the original sample. e.the Ksp of barium iodate=(molarity of IO3- in original sample)/2=0.00331M/2=0.001655M   since each Ba(IO3)2 produces one mole of Ba2+ and 2moles of IO3-

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