Answer to Question #225184 in Organic Chemistry for Khabyaby

Question

1. The Concentration of HCl, a strong acid, is 0.5 mol/L. If 20 mL HCl is needed to titrate 40 mL of NaOH, what is the Concentration of NaOH?

2. What would be the molar concentration of a HCL solution if 25.0 mL of the solution is neutralized by 15.5 mL of 0.800 mol/L NaOH?

3. a) Explain what an equivalence point is in a titration.
b) What is the purpose of an indicator in the solution with the unknown concentration?

4. A strong acid and a weak acid that are both 1.0 mol/L react differently with zinc. Choose two acids and with the aid of equations and dissociation, explain why this is the case.

Answer 1

Equivalence point: point in titration at which the amount of titrant added is just enough to completely neutralize the analyte solution. At the equivalence point in an acid-base titration, moles of base = moles of acid and the solution only contains salt and water.

The common application of indicators is the detection of end points of titrations. The colour of an indicator alters when the acidity or the oxidizing strength of the solution, or the concentration of a certain chemical species, reaches a critical range of values.

A strong base reacts with water 100% to produce and it's conjugate acid is very weak, meaning it does not react with water at all. A weak acid or base will react partially with water to produce the hydronium ion or the hydroxide ion, respectively and the conjugate base and conjugate acid, respectively.