Question #b8448
1 Answer
Explanation:
Your strategy here will be to

use the molarity and volume of the target solution to find how many moles of solute it must contain

use cesium chloride's molar mass to determine how many grams of cesium would contain that many moles

use the stock solution's known percent concentration by mass to determine what mass of the stock solution would contain that many grams of cesium

use the stock solution's density to determine the volume of solution that would contain that many grams of solution
As you know, molarity is defined as moles of solute, which in your case is cesium chloride,
#color(blue)(c = n/V implies n = c * V)#
#n = "0.100 M" * 500.0 * 10^(3)"L" = "0.0500 moles CsCl"#
Use the compound's molar mass to help you find the mass of cesium chloride that would contain this many moles
#0.0500 color(red)(cancel(color(black)("moles CsCl"))) * "168.37 g CsCl"/(1color(red)(cancel(color(black)("mole CsCl")))) = "8.4185 g CsCl"#
Now, the stock solution is
This means that the mass of stock solution that would contain this many grams of cesium chloride is equal to
#8.4185 color(red)(cancel(color(black)("g CsCl"))) * "100.0 g stock"/(40.0color(red)(cancel(color(black)("g CsCl")))) = "21.046 g stock"#
You know that this stock solution has a density of
In your case, the volume that contains
#21.046 color(red)(cancel(color(black)("g stock"))) * "1 mL"/(1.43color(red)(cancel(color(black)("g stock")))) = "14.717 mL"#
Rounded to three sig figs, the answer will be
#V_"stock" = color(green)("14.7 mL")#
So, to prepare your target solution, take