You are given four different aqueous solutions and told that they each contain NaOH, Na2CO3, NaHCO3, or a mixture of these solutes. You do some experiments and gather these data about the samples. Sample A: Phenolphthalein is colorless in the solution. Sample B: The sample was titrated with HCl until the pink color of phenolphthalein disappeared, then methyl orange was added. The solution became pink. Methyl orange changes color from pH 3.01 (red) to pH 4.4 (orange). Sample C: Equal volumes of the sample were titrated with standardized acid. Using phenolphthalein as an indicator required 15.26 mL of standardized acid to change the phenolphthalein color. The other sample required 17.90 mL for a color change using methyl orange as the indicator. Sample D: Two equal volumes of the sample were titrated with standardized HCl. Using phenolphthalein as the indicator, it took 15.00 mL of acid to reach the equivalence point; using methyl orange as the indicator required 30.00 mL HCl to achieve neutralization. Identify the solute in each of the solutions.

One half liter (500. mL) of 2.50 M HCl is mixed with 250. mL of 3.75 M HCl. Assuming the total solution volume after mixing is 750. mL, what is the concentration of hydrochloric acid in the resulting solution? What is its pH?

When carbon dioxide dissolves in water it reacts to produce carbonic acid, H2CO3(aq), which can ionize in two steps. H2CO3(aq)HCO3(aq)+H+(aq)Kc1=4.2107HCO3(aq)CO32(aq)+H+(aq)Kc2=4.81011 Calculate the equilibrium constant for the reaction H2CO3(aq)CO32(aq)+2H+(aq)