Question

Magnesium hydroxide is one of the components of hard water buildup. CLR, a common commercial product used to remove hard water buildup, contains lactic acid (CH3CH(OH)COOH). CLR works to remove hard water build up by a chemical reaction that dissolves the compounds. In this case, the reaction that occurs is: → 2H2O() + Mg(OH)2(s) + 2 CH3 CH(OH)COOH(aq) Mg(CH3 CH(OH)COO)2(aq) Depending on the mixture, CLR contains 12-18% by mass of lactic acid (1.4-2.0 M), and is commonly sold in 28 fl oz (830 mL) bottles. 1: It was estimated that there's 1.30 g of magnesium hydroxide (MM = 58.32) build up on a faucet. What volume of 1.40 M lactic acid would be required to fully dissolve it? 2: How much lactic acid (MM = 90.08 g/mol) was consumed in this reaction? Calculate the answer in grams. 3: Suppose in Question 1, you were impatient and you used the entire 830 ml bottle instead. Since you don't want to waste it, you decide to pour it back in the bottle. Calculate the total mass of lactic acid present in 830 mL, and what the new %lactic acid by mass would be after the reaction (density = 1.05 g/mL for the solution). Assume that the volume and mass of the products of the reaction are negligible.