If 15 tablespoons of NaCl are added to 16 cups of water, what is the sodium molarity of the solution?

Question

It has long been mentioned that adding a peeled potato chunk to a soup and then removing it, is a good way to remove excess salt. In addition, assume that 1.0 tablespoon equals 3.0 teaspoons; and 1.0 cup equals 0.237L.

If 15 tablespoons of NaCl are added to 16 cups of water, what is the sodium molarity of the solution? It has been determined that a specific sized potato chunk removed ½ a teaspoon amount of sodium. If 3 potato chunks were added, and removed. What is the new solution molarity of sodium?

Answer 1

1 ml = 0.067628 tbsp

2.16 g/cm³ (density of salt)

(15 T/ 16 cup) x (1 ml/0.067628 T) x (1 cm3/1 mL) x (2.16 g/cm³ ) = the number of grams of NaCl/cup = 29.943 g/cup

(29.943 g/cup) x (1 mol/58.44 g) x (1.0 cup/0.237L) = 2.162 mol/L

2 sig fig answer: 2.2 mol/L Na

This solution uses some assumptions that are not entirely true... For example, that for NaCl, 1 gm = 1 cm^3. This is true for water, but not necessary for NaCl.

You can repeat the calculations with the potatoes.