Answer:
15.0g/L is the concentration of nickel(II) chloride contaminant in the original groundwater sample.
Step-by-step explanation:
Based on the reaction:
NiCl2 (aq) + 2AgNO3 (aq) -> 2AgCl (s) + Ni(NO3)2 (aq)
Where 1 mole of NiCl₂ reacts producing 2 moles of AgCl.
To solve this problem, we need to convert mass of AgCl to moles to know the moles of NiCl₂ that reacts. With these moles and the volume of the sample (250mL = 0.250L), we can determine the molar concentration of the contaminant in the sample
Moles AgCl:
8.3g of AgCl were collected. In moles (Molar mass AgCl: 143.32g/mol):
8.3g AgCl * (1mol / 143.32g) = 0.05791 moles AgCl
Moles NiCl₂:
As 2 moles of AgCl are produced from 1 mole of NiCl₂. Moles of NiCl₂ are:
0.05791 moles AgCl * (1 mole NiCl₂ / 2 moles AgCl) = 0.02896 moles NiCl₂
Molar concentration:
0.02896 moles NiCl₂ / 0.250L =
0.1158M
In g/L (Molar mass NiCl₂: 129.6g/mol):
0.1158 mol / L * (129.6g / mol) =
15.0g/L is the concentration of nickel(II) chloride contaminant in the original groundwater sample.