Discussion For Titration and Preparation of Standard Solution

 

Discussion 

A standard solution is one whose concentration concentration is known exactly. Standard solution of a solid can be prepared by weighing a mass of the solid and dissolving it in a known volume of solution. In part A of this experiment, we prepared a standard solution of sodium carbonate. It will then be used later in part B.

The “Standard solution sodium carbonate” prepared in Part A is used to determine the concentration of dilute hydrochloric acid by titration method. Hence, it is very important to obtain the standard solution of sodium carbonate. This procedure is also known as standardising the hydrochloric acid.

There are some recommendation for this experiment which is we need to weight sodium carbonate solid more than two trials to get accurate and average result. This will increase the accuracy of the value at the end of experiment.

Titration is a technique for determining either the concentration fo a solution of a unknown molarity or the number of moles of a substance in a given sample. A chemical reaction is used for this purpose and the reaction must be fast, be complete and have a determinable end point. The reactions of strong acid and bases generally meet these criteria and acid-base titration are among the most important examples of this technique. In this experiment, the sample is hydrochloric acid and sodium carbonate. The sodium carbonate as base substance and hydrochloric acid as acid substance where the concentration of hydrochloric acid is unknown. Given that, the concentration of the base are 0.2M

 

 

An indicator is used as signal the point which the titration is stopped, the indicator that we used in this experiment is phenolphthalein. If we use base as titrant and acid as solution in the volumetric flask, at the end point, the solution in the solution in the the volumetric flask will turn to light pink. If we use acid as titrant and base as solution in the volumetric flask, at the end point, the solution in the volumetric flask will turn to colourless. For this experiment, the solution from the colourless to light pink because we use the base as titrant.

From the experiment that we did, the actual molarity for Na2CO3 solution that we get is 0.21M. If we double the mass of hydrochloric acid, the molarity will be 0.1M due to the double of volume of Na2CO3 used during the titration. Is it unnecessary for us to know the exact concentration of HCL solution in order to determine the concentration of the base because the mol of acid cannot change when we dissolve the mass of HCL in the unknown volume of water.

In this experiment, there are some mistake like we measured the HCL solution inaccurately using the pipette. Hence, the molarity of solution obtained will not be be perfect due to carelessness occured. To overcome this problem, our eyes must be directly perpendicular to the scale of pipette to get the perfect measurement measurement without any errors. That’s the problem had affect our result. That’s why our result is not precise and accurate to the correct value.

 

There is some recommendation for this experiment. First, we must ensure that there are no bubbles trapped at the tip of the burette during the filling of Na2CO3 solution. Second, we must avoid from make a parallax error for most of the measured content