Question

O STORCROMETRY Solving for a reactant in solution One way the U.S. Environmental Protection Agency (EPA) tests for chloride contaminants in water is by titrating a sample of silver nitrate solution. Any chloride anions in solution will combine with the silver cations to produce bright white silver chloride precipitate. Suppose an EPA chemist tests a 200 ml sample of groundwater known to be contaminated with nickel() chloride, which would react with silver nitrate solution like this: NiCl(aq) + 2 AgNO3(aq) + 2 AgCl(s) + N(NO) (0) The chemist adds 51.0 mm silver nitrate solution to the sample until silver chiondestops forming. She then washes, dries, and weigh the precipitate. She finds she has collected 4.5 mg of silver chloride ends were the correct number of significant Calculate the concentration of nickel(II) chonde contaminant in the original groundwater sampleBere you digits.

Answer 1

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U2 - Wintono As Nich(12) Nila) 4 12 et (0) Now, i mole of Nich reacts with the 2 mole of AgNO₃ form 2 mol of Agce Molecular weight of AgNO3 = 169.87 gimol . . Molecular weight of Agee = 143.32 g imel 1. So, No. of moes of Ance formed = 4.5 mg mo 143.329 C e na is 14.5 10 Imol (143:32 So, No. of moles of Agnoused = no. of moles of Agae There is formed So, the concentration of AgNO₃ Solutions- 5100 mm ). = (510x10=3169•67) 84:51.0*10*3km So, Volume of Agnos used to titrate 200 me of Nicia Solution, (405x10^3),3169.87 (9/01) 143.32 /(mol)

Nicl2 (aq) 4 ang 1902(12) — ang d (s) + wi(NO),(22) so, concentration of Niely - Concentration of co As Nich(12) Nilhas + 2 et (all. Now, 1 mole 07 Niels reacts with the 2 mole of of my NO₂ No. form 2 mol of Agce Molecular weight of Ag NO3 = 169.87 g/mol . Molecular weight of Agee - 143• 32 gimo! formed = ad = 4.5 mg mo 143.329 Se, No.of mole's Of Agu 14.5 X 10 14 3:32 So, No. of mole s 07 Ang used = no. of moles of Agil formed ). So, the concentration of AgNO3 Solutions, 5100 mm = (51.0x10-3169067):510x10=3 km So, Volume of AgNo used to titrate 200 me of Nica Solution, (4.587063 )*769.87 (a/mol) ( 51.0x103x169.87)g! V = 143-32 m 69.87 (9/mou. -(49.65.350 m2 Volume of Niciz Sometion, v= 200 mL Streangth of al Solution = s, (g/mol) ) mL Volume of AgNO3 Solution used =12 = (405 Streangth of Ag nog solution = S, -(51.0X10-3x169.87% I .

We knew, in case of tit ratton : vs, = V₂ S2 63.5 ) Smt x (51.0 * 70-3x/69187) 9h 200 (me) 4.5 x 51.0x10 3 169.87 143.32 x 200 x 169.87 mg/L 4.5 x 51.0 - 143, 32 x 200 - 1.36 So, concentration of U-21-36 So, concentration of Nietz = 136 -0.68 mg/ (one a significant Cafter point digit taken ~0.7