# Chemistry

posted by
**Steve**
.

A sample of a mixture containing only sodium chloride (NaCl) and potassium chloride (KCl) has a total mass of 4.000g. When this sample is dissolved in water and excess silver nitrate is added a white precipitate (AgCl) forms. After filtration and drying, this precipitate had a mass of 8.5904g. Calculate the mass percent of each component in the mixture.

--58.5x + 74.5y = 4

143.5 (x+y) = 8.5904

Using system of equations,

x = 0.028 y=0.031

NaCl = 58.5*0.028 / 4 *100 = 43 %

KCl = 74.5 * 0.031 / 4 *100 = 57 %

Is this right?

Your values for %NaCl and %KCl are close (within 1%) but for the life of me I can't figure out what you did?

What is X and what is Y? I wonder if your equations gave you close to the correct value by chance. I know you solved two equations simultaneously. Also, since 4.000 is to 4 places and 8.5904 is to 5 places, I think you should use more signifivant figures than you have for NaCl, KCl, and AgCl.