As a food chemist for a major potato chip company, you are responsible for deter

Question

As a food chemist for a major potato chip company, you are responsible for determining the salt content of new potato chip products for the packaging label. The potato chips are seasoned with table salt, NaCl. You weigh out a handful of the chips, boil them in water to extract the salt, and then filter the boiled chips to remove the soggy chip pieces. You then analyze the chip filtrate for Cl concentration using the Mohr method.

First you prepare a solution of silver nitrate, AgNO3, and titrate it against 0.500 g of KCl using the Mohr method. You find that it takes 61.4 mL of AgNO3 titrant to reach the equivalence point of the reaction.

You then use the same silver nitrate solution to analyze the chip filtrate in a Mohr reaction, finding that the solution yields a rusty brown precipitate when 47.7 mL of titrant is added.

If the sample of chips used to make the filtrate weighed 93.0 g , how much NaCl is present in one serving (145 g) of chips?

Explanation / Answer

61.4ml AgNO3 = 0.500g KCl
47.7ml AgNO3 = (47.7/61.4)*0.500 = 0.3884g KCl

You want NaCl:
Molar mass KCl = 39.098+35.453 = 74.551g/mol
Molar mass NaCl = 22.99+35.453 = 58.443
0.3884 * 58.443/74.551 = 0.2797 = 0.3045g NaCl

This is in 93g potato chips
145g serving will contain : 0.3045*145/93 = 0.4747g NaCl.

0.4747g NaCl is present in one serving (145 g) of chips

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