Acid-Base Titration

For every Titration experiment, a solution of accurately known concentration especially for the standard solution is added to another solution of unknown solution that helps to determine its concentration based on the volume of the solution used. The chemical reaction between the two solutions has to be completed before the determination of the concentration of the unknown solution.

 In this case, a known concentration of Sodium hydroxide solution (NaOH) (0.200 M) is used to determine the concentration of 60.0 ml Hydrochloric acid (HCL). The solution of sodium hydroxide is allowed to react with HCL acid in intervals of 5 ml by volume. The change in PH should be recorded for every reaction interval. As the solution of NaOH reacts with the acid, the hydroxide ions from the base and the hydrogen ions from the acid react to produce water. The PH of the solution increases as each drop of sodium hydroxide reacts with the hydrochloric solution. The PH of the solution in the titration flask continues to rise to the point of 1.93 where it rises more steadily to PH 7 where the reaction is said to be complete because enough of the base has reacted with the acid solution. The acid is said to be neutralized by the base, and the point is called the equivalence point. The titration of a strong acid and a strong base has a PH of 7 at the equivalence point. The sodium and Chloride ions that reacted are in the solution, but they do affect the PH of the solution. After the equivalence point, there are no additional hydrogen ions to react with the base, and hence the further addition of sodium hydroxide solution will only increase the PH since the concentration of the solution is basic. Further addition of sodium hydroxide does not result to increase in PH and reaches at a point of 12.3.

At PH 7 (equivalence point), the volume of NaOH used is 30 ml, and its concentration is 0.200M. The initial volume of HCl solution was 60.0 mL.

The reaction of the titration experiment is:

HCL (aq) + NaOH (aq)                H₂O (l) + NaCl (aq)

The net ionic equation for the experiment is:

H⁺ (aq) + OH^-(aq)              H₂O (l)                                       

The mole ratio of the reaction is 1:1, and helps to calculate the concentration of the hydrochloric solution.

Molarity = No. of moles /Volume used (L)

No. of Moles for NaOH used in the reaction = Molarity * Volume

                                                                              = 0.2*0.03 = 0.006 moles

From the mole ratio of 1:1, the number of moles of HCL that reacted equals to 0.006 moles

Thus, the molarity of the HCL solution is:

0.006 moles/ 0.06 = 0.100 M HCL

The concentration of HCL that reacted in the experiment is 0.100 M HCL.   

Sherry Roberts is the author of this paper. A senior editor at MeldaResearch.Com in urgent custom research papers. If you need a similar paper you can place your order from nursing school papers services.