Question

A piece of lithium metal is added to a beaker that contains water and phenolphthalein. using what you know about the properties of bases, choose the best explanation for what you observe. the phenolphthalein is turning pink because an acid is forming. the phenolphthalein is turning pink because a base is forming. the phenolphthalein is turning pink because the reaction is at equilibrium. a beaker containing a small amount of red liquid.

Answer 1

The pink color change of phenolphthalein when lithium is added to water indicates the formation of a basic solution, due to the production of lithium hydroxide.

Step-by-step explanation:

When lithium metal is added to water containing the indicator phenolphthalein, the phenolphthalein turns pink. This color change indicates that a base is forming, not an acid. Lithium reacts with water in a single displacement reaction to produce lithium hydroxide (a base) and hydrogen gas. Since phenolphthalein turns pink in basic solutions, the color change clearly signals the presence of a basic environment. According to our understanding of acids and bases, phenolphthalein is a chemical indicator that is colorless in acidic solutions and turns pink in basic solutions. The reaction of lithium with water to form lithium hydroxide increases the basicity of the solution, resulting in the pink coloration due to the low hydronium ion concentration (pH > 8.3). Phenolphthalein is an acid-base indicator useful for detecting the pH level of a solution.