When a sample of oxalic acid (H2C2O4), which is a diprotic acid (both H-atoms are acidic), is titrated with 0.250 M potassium hydroxide solution, 24.09 mL of the potassium hydroxide solution are required to neutralize the acid.  How many grams of oxalic acid where present in the sample? 2 KOH(aq)  +  H2C2O4(s)  →  K2C2O4(aq)  +  2 H2O(l) Your answer should have 3 significant figures. Answer:

The concentration of SO42– ions in a 45.0 mL sample of seawater is determined by adding a solution of BaCl2 and precipitating the SO42– as BaSO4. After the precipitate is filtered from the solution, it is dried and weighed. If the mass of BaSO4 recovered is 0.315 g, what is the sulfate concentration of the seawater sample? Express your answer in mmol/L.

sample of solid calcium hydroxide is allowed to stand in water until a saturated solution is fomed. A titration of 75.00 ml of this solution with 5.00' 10^-5 requires 36.60 mL of the acid to reach the end point. What is the molarity of Ca(OH) 2 solution? Ca(OH) 2 (aq)+HCl(aq)CaCl 2 aq)+H 2 O (l) ( Note: This is an unbalanced reaction. Balance before quantitative calculations)

A chemistry student needs to standardize a fresh solution of sodium hydroxide. He carefully weighs out 214.mg of oxalic acid H2C2O4 , a diprotic acid that can be purchased inexpensively in high purity, and dissolves it in 250.mL of distilled water. The student then titrates the oxalic acid solution with his sodium hydroxide solution. When the titration reaches the equivalence point, the student finds he has used 91.8mL of sodium hydroxide solution. Calculate the molarity of the student's sodium hydroxide solution. Be sure your answer has the correct number of significant digits.