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 63.0 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 46.9 mL of titrant is added.

If the sample of chips used to make the filtrate weighed 82.0g, how much NaCl is present in one serving (155g ) of chips?

Answer 1

To determine the salt content in the potato chips, you used a method called the Mohr method.

Step-by-step explanation:

To determine the salt content in the potato chips, you used a method called the Mohr method. In this method, you prepared a solution of silver nitrate and titrated it against KCl to find the volume of silver nitrate required to reach the equivalence point. Then, you used the same silver nitrate solution to analyze the chip filtrate and found that it required a certain volume of titrant. By using this data, you can calculate the amount of NaCl in one serving of chips.

Answer 2

One serving of potato chips contains 0.557 g of NaCl.

We know that 63.0 mL (0.0630 L) of AgNO₃ titrated 0.500 g KCl.

Molar mass of KCl = 74.55 g/mol.

Moles of KCl used = 0.500 g / 74.55 g/mol = 0.00671 mol.

Molarity of AgNO₃ = 0.00671 mol / 0.0630 L = 0.1065 M.

Since the reaction is AgNO₃ + NaCl -> AgCl + NaNO₃, the moles of NaCl are equal to the moles of AgNO₃ used.

Moles of NaCl in the filtrate = 0.00502 mol.

Molar mass of NaCl = 58.44 g/mol.

Mass of NaCl = 0.00502 mol * 58.44 g/mol = 0.294 g.

Mass of NaCl per gram of chips = 0.294 g NaCl / 82.0 g chips

= 0.00359 g NaCl/g chips.

Mass of NaCl in one serving = 0.00359 g NaCl/g chips * 155 g chips

= 0.557 g NaCl.