# Molarity Of A Solution By Performing A Titration Biology Essay

In Natural scientific discipline, scientists plan experiments and analyze them, to back up their claims. Scientists use particular units like Grams ( g ) , Milliliters ( milliliter ) and Molars with a symbol of M. Molars is a term showing morality of each compound or component in a chemical reaction. Molarity is the lone manner scientists use to mensurate the concentration of a solution. Concentration of a solution means how much solute ( which is the substance that is being dissolved by the dissolver, which is the liquid that dissolves the solute ) is present in a given sum of solution. To happen the concentration ( C ) we divide, moles of solute ( n ) , by the volume of a solution ( V ) . The undermentioned expression is being used: .Another expression can be used to find Molarity ( M ) is by spliting the moles of solute ( mol ) by litre of solution ( L ) , to happen the concentration: . However, to find the molar concentrations of a solution of acidic and basic solutions, which are frequently used to change over back and Forth between moles of solutes and volumes of their solutions, titration is used. Titration is when one solution is added to another solution until a chemical reaction between the solution has run to completion. The first solution is called the titrant, which is used to titrate the other solution. The completion of the reaction is normally shown by a alteration of colour caused by a substance called an index, like phenotolphthatein. The undermentioned expression is used to find titration in a chemical reaction: C1 A- V1 = C2 A- V2. C stands for the concentration, and V is the volume in an acidic and basic solution. This expression enables scientists to distinguish acids from bases and, besides determine the concentration and volume ( Titration ) of a chemical reaction.

Purpose: Determine the molar concentration of a NaOH solution by executing a titration utilizing 0.100 M HCl.

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Hypothesis:

Common unites used to mensurate solutions in labs are gms, millilitre and molar concentrations. Molarity ( M ) is fundamentally the step of the concentration of a solution. However when it comes to acidic and basic solution, titration is used to happen the volume and concentration of a solution. Titration is when one solution is added to another solution until a chemical reaction between the solutions has run to completion. The completion of the reaction between the solution is shown by a alteration of colour caused by a substance called an index. In this experiment I predict that the HCl solution will fade out wholly, when a light pink colour occurs, because when NaOH was tested by phenolphthalein index, it gave a light pink colour.

## Method:

25mL of 0.10 M HCl solution was measured in a calibrated cylinder, to so reassign it into 50mL Erlenmeyer flask, to be accurate and exact.

Then, 50mL of NaOH with unknown concentration was measured.

The 50mL Burette was rinsed with a little sum NaOH, to avoid mixing H2O with NaOH. After rinsing the burette, NaOH solution was filled till the top.

A beaker was labeled “ HCl ” under the burette. After that the turncock of the burette was opened, to let air bubbles to get away from the burette.

Three droplets of phenolphthalein index were added to the HCl in the Erlenmeyer flask. Then, the Erlenmeyer flask was placed under the NaOH burette, and the turncock of the burette was opened to let a few beads of the NaOH to flux into the flask while continuously twirling the flask. Then we observed the colour changes that occurred. After that, we easy continued to add NaOH while twirling the flask.

When a swoon pink colour appeared and persisted for about 10 seconds or more of swirling of the flask, so the end point was reached. Which means that the HCl solution was wholly dissolved in NaOH.

After that, the end point was reached, and the volume of NaOH was recorded.

Then, we calculated the molar concentration of the NaOH solution.

Several tests of titration were made, to hold an exact and accurate initial and concluding readings.

After the 3 tests, we calculated the mean concentration of NaOH solution.

Independent variable: The variable that changed was the initial reading. As we started from 0mL in test 1 and 2, so we changed and started from 13.2mL in tests 3 and in test 4 we started at 26.2mL.

Dependant variable: The variable that was affected from the altering variable was the concluding initial readings, which will impact on the volume of NaOH solution needed to neutralize HCl.

Controlled variable: The variable controlled was the NaOH solution in the burette, because we physically closed and opened the turncock to let beads of NaOH solution to respond with the HCl solution in the Erlenmeyer flask.

## Materials

Ringing base and clinch

50 milliliters Erlenmeyer flask

50 milliliter Burette

One 50 milliliter beaker

Filter funnel

0.100 M HCl

150 milliliter of Unknown concentration of NaOH

Phenolphthalein ( Indicator )

## Safety factors

Lab coat

Safety spectacless

Baseball gloves

Avoid posing, while making an experiment.

Follow instructor ‘s instructions.

Use right equipments, in a right manner.

## Reading of NaOH volume:

Tests

Observation

Trial 1

0mL

13.0mL

The solution was perfect. It gave a light pink colour.

Trial 2

0mL

13.2mL

The solution turned to a light pink colour. This was considered perfect.

Trial 3

13.2mL

26.2mL

The solution became perfect once more. As, it gave a light pink colour. My spouse and I observed that the alteration of the colour will happen by duplicating the initial burette reading.

Trial 4

26.2mL

38.5mL

Our observation was wrong, as the solution was overshot, due to times restriction, because we rushed to complete the experiment. However, if we had more clip, our observation, may turn correct.

Figure.1 Initial and concluding burette reading and observation of NaOH volume.

## Volume of NaOH needed to neutralize HCl:

Trial 1

Trial 2

Trial 3

Trial 4

Observations

13.0mL

13.2mL

13.0mL

12.3mL

To happen the volume of NaOH, we subtracted the initial burette reading by the concluding burette reading. The first three tests, they all had common Numberss, which is 13. This explains the truth of the point reached, when HCl solution was wholly dissolved in NaOH. Therefore when the solution becomes light pink, it contains merely NaOH solution. In trail 4, it was 12.3, which was overshot.

Figure.2 Trials and observation of the volume of NaOH solution needed to neutralize HCl solution.

## Discussion

The experiment investigates HCl + NaOH A® NaCl + H2O equation and determines the molar concentration of NaOH solution by executing a titration utilizing 0.100 M HCl. The experiment began by mensurating 25mL of HCl into an Erlenmeyer flask. Then we measured 50mL of an unknown concentration of NaOH and filled till the top of a Burette. We added three beads of phenolphthalein index in the HCL solution. To get down the experiment we placed the HCL under the burette of NaOH solution and opened and closed the turncock of the burette. Till a light pink colour occur, this meant that all the HCl solution was dissolved in NaOH. In trail one, two and three, the solution gave a light pink colour, which was perfect. We observed that the alteration of the colour will happen by duplicating the initial burette reading. However, our anticipation was wrong, because in trail 4 the solution was overshot, which gave a dark pink colour. The solution was overshot, due to times restriction, as we rushed to complete the experiment. In trails 1, 2 and 3, the volume that was needed to neutralize the HCl solution, was 13mL.But in trail 4, it was 12.3mL, which was overshot. After these observation and computation, the molarilty was determined by first happening the concentration of the NaOH solution utilizing the titration expression: C1 A- V1 = C2 A- V2

Meter

0.100 M A- 25mL = C2 A- 50mL

C2 =

C2 = 0.05 M

After happening the concentration, we need to happen the mol of NaOH solution utilizing:

0.05 M =

n = 0.05 M A- 50mL = 2.5 mols

Finally, utilizing the mols and volume of NaOH solution, the molar concentration can be determined by utilizing its regulation:

M= = 50 M

50 M is the molar concentration of a NaOH solution by executing the titration utilizing 0.100 M HCl.

## Mistakes and Improvements

There were systematic and random mistakes in this experiment that affected the consequences. In this experiment, we did four tests in entire. All three tests were perfect and had a light pink colour.However ; the 4th test became overshot, and had a dark pink colour. Trial four was overshot due to clip restriction, as we rush to make complete it. We opened the turncock and NaOH solution was fluxing rapidly in the HCl solution that is another ground for the solution to go overshot. Another mistake was that we did n’t make plenty trails. To go accurate and exact tests should be made, to better our experiment. In all our four trails we were n’t concentrating every bit much, as we rushed more on the last trail. To better our experiment we should concentration and wait for the NaOH solution to wholly fade out in the HCl. We besides wasted a batch of NaOH solution, as we started from 0 twice, we should get down from the old figure, that the NaOH solution was wholly dissolved in HCl solution. Besides, we wasted the HCl solution, when we rapidly poured it and slop about 5mL of the 25mL solution. Random mistakes affected the consequences, as it is all based on computation. However the systematic mistakes did impact the consequences excessively, observation and collected informations. To better all these mistakes, we should concentration, non hotfoot and be patient, to let the truth and completion of the reaction.

## Decision

This lab study investigates a balanced equation of HCl + NaOH A® NaCl + H2O. It determined the molar concentration of a NaOH solution by executing a titration utilizing 0.100 M HCl. The molar concentration of NaOH is equal to 50 M, Harmonizing to the computation. We found the molar concentration by utilizing the concentration, molar concentration and titration expressions. Besides, we used tests, to detect the alterations in the reaction between NaOH and HCl solutions.

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