Use the equation of sodium chloride dissolving in water to complete the activity.
NaCl(s) ⇄ Na+(aq) + Cl–(aq)
A student is testing two clear liquids. One liquid is water that has been modified to have a basic pH. The other liquid is a sports drink that contains added electrolytes, including Na+(aq). How can the student use the equilibrium reaction of sodium chloride to determine which liquid is which? In three to five sentences, explain your answer.
Hint: Refer to Unit 5 lesson 2 page 3 to find the answer.
(4 points)
The student can use the equilibrium reaction of sodium chloride dissolving in water to determine which liquid is which by observing the ions present in each liquid. If the basic pH water has been modified to be basic, it may contain hydroxide ions (OH-) that can react with sodium ions (Na+) to form sodium hydroxide (NaOH) and water. This reaction would shift the equilibrium towards the left, decreasing the concentration of Na+ ions in the solution. In contrast, the sports drink containing added electrolytes, including Na+(aq), would maintain a high concentration of Na+ ions in the solution, shifting the equilibrium towards the right. By testing the presence of Na+ ions in each liquid, the student can identify which liquid is the basic water and which one is the sports drink.
Chromate ions react according to the following equation, where the left side of the reaction is yellow and the right side is orange.
CrO42– + 2H+ ⇄ Cr2O72– + H2O
A student adds sodium hydroxide (NaOH) to the solution at equilibrium. In one to two sentences, describe and explain any changes to the solution that the student will observe.
Hint: Refer to Unit 5 lesson 3 pages 2-3 to find the answer.
(2 points)