Question

Question #1565c

Answer 1

An answer cannot be given without providing the mols of AgNO3 and the volume of the solution.

Answer 2

The molarity of the silver nitrate solution is 0.394 mM.

The balanced chemical equation for this double replacement reaction looks like this

`AgNO_(3(aq)) + KCl_((aq)) -> AgCl_((s)) + KNO_(3(aq))`

Notice that you have a `1:1` mole ratio between silver nitrate and potassium chloride, which means that you need 1 mole of silver nitrate for every 1 mole of potassium chloride in order for the reaction to take place.

The net ionic equation for this reaction is

`Ag_((aq))^(+) + Cl_((aq))^(-) -> AgCl_((s))`

You know the mass of the potassium chloride sample, which means that you can use the compound's molar mass to determine how many moles of the compound reacted

`0.780 * 10^(-3)cancel("g") * "1 mole KCl"/(74.5513cancel("g")) = 0.0105 * 10^(-3)"moles KCl"`

This is equal to the number of moles of silver nitrate you need in order for the reaction to precipitate all the `Cl^(-)` ions present in solution

`n_(AgNO_3) = n_(KCl) = 0.0105 * 10^(-3)"moles"`

Now use the volume of the silver nitrate solution to determine its molarity

`C = n/V = (0.0105 * 10^(-3)"moles")/(26.6 * 10^(-3)"L") = 3.94 * 10^(-4)"M" = color(green)("0.394 mM")`