Standard liquid solutions, like acids, are readily available and simple to prepare. The technique used in the quantitative analysis of any chemical is titration. A method for comprehending behaviour known as quantitative analysis makes use of statistical and mathematical modelling, observation, and investigation. Quantitative investigators use data to illustrate a particular fact.

The analysis often reveals any chemical substance's molarity or molality, or strength of solution and concentration. Compounds called indicators are introduced to analyte solutions along with titrant. Thus this chemistry experiment explains the strength and molarity of the given HCl solution with the 0.05M Na2CO3 solution.

Table of Content

• Aim

• Apparatus required

• Theory

• Procedure

• Result

Aim

To determine the strength and molarity of the given HCl solution with the given 0.05M Na2CO3 solution.

Apparatus Required

1. Burette stand

2. Burette

3. Conical flask

4. Measuring flask

5. Pipette

6. Glass rod

7. Funnel

8. Watch glass

9. Wash bottle

10. Methyl orange

Theory

• A standard solution is one whose concentrations are precisely known. 

• By titrating hydrochloric acid with a standard sodium carbonate solution while employing methyl orange as an indicator, one can measure the molarity of the acid.

• By multiplying the acid's molarity by its molecular mass, which is 36.5, the strength of the solution given is calculated.

Procedure

Determination of Strength and Molarity of Given HCl solution with the given 0.05M Na2CO3

1. Using distilled water, clean the burette.

2. Fill the burette using the provided HCl solution after rinsing it. 

3. Pipette 20 ml of the given Na2CO3 solution into a cleaned conical flask after rinsing the pipette with the provided Na2CO3 solution. 

4. After adding 2-3 drops of methyl orange into the conical flask containing 20mL of Na2CO3, place it over the tile just below the tip of the burette.

5. Record the burette's initial value and gently run the drops of acid solution to the conical flask until the solution's colour shifts from yellow to pale pink.

6. Keep track of the final measurement and calculate the amount of HCl solution employed.

7. The procedure should be repeated to measure at a minimum of three concordant readings.

Observations

Result

The result of the chemistry experiment on the determination of strength and molarity of the given HCl solution with the given 0.05M Na2CO3 solution verified that:

The strength of the given HCl solution is ( _ gL-1).

Precautions

• Handle chemicals and apparatus with caution.

• Every apparatus should be rinsed with distilled water and dried before starting the experiment.

• To prevent adding additional distilled water beyond the line on the measuring cylinder's neck, add the final few droplets using a pipette.

• If any acid spills on your body, immediately wash it off with water. Apply a little ointment after that.

• After the completion of the experiment, wash your hands thoroughly.

Lab Manual Questions

1. What is the aim of transferring solutions using a glass rod?

Ans: Solutions are poured using glass rods to prevent spillage. A glass rod placed against a beaker's pouring edge enables the solution to run down the glass rod and into the collecting vessel, as opposed to splashing beyond the lip.

2. Why does not the pipette blow out the final drop?

Ans: Due to the surface tension, a tiny drop of liquid remains in the pipette after the last drop is added, preventing the last drop from being blown out. Moreover, the design of pipettes ensures that this drop won't have an impact on the empirical value.

3. Why are concentrated HCl not used in this experiment?

Ans: When using concentrated acids, the reaction is extremely violent and the mixture gets hot. This speeds up the process much more and the liquid within may foam. The process is significantly under control when the acid is diluted.

4. What purpose does a burette serve?

Ans: A burette is a titration tool made of glass. It is utilised for the regulated distribution of any volume of liquid within a specific range.

Viva Questions

1. Mention a few common indicators?

Ans: Methyl orange, phenolphthalein, starch, etc.

2. Define molarity.

Ans: The number of moles of a solute per litre of a solution is known as molarity. Another term for molarity is the molar concentration of a solution.

3. What is the molarity formula?

Ans: The molarity formula is \[{M_1}{V_1} = {M_2}{V_2}\] 

4. How to calculate the molecular mass of HCl?

Ans: Molecular mass of HCl= Molar mass of H+ + Molar mass of Cl-=1+35.5=36.5g. Hence, the molar mass of HCl is 36.5g.

5. What is the equivalent mass of HCl?

Ans: The equivalent mass of HCl is 85.1g.

6. How to calculate the strength of the solution of HCl?

Ans: Volume of HCl employed to neutralise 0.05 M of 20 ml of Na2CO3 solution is given by:

The volume strength formula is

\[\frac{{{M_1}{V_1}(HCl)}}{{{M_2}{V_2}(N{a_2}C{O_3})}}=\frac{{Stoichiometriccoeffecientof(HCl)}}{{Stoichiometriccoeffecientof(N{a_2}C{O_3})}}\] 

\[\frac{{{M_1} \times a}}{{0.05 \times 20}} = \frac{2}{1}\] 

\[{M_1} = \frac{{2 \times 20 \times 0.05}}{a} = \frac{2}{a}\] 

\[Strength{\rm{ }}of{\rm{ }}HCl = \frac{2}{a} \times 36.5g{L^{ - 1}}\] 

7. What is the endpoint?

Ans: The end point of a titration is the point where the reaction is almost finished. Once a chemical process reaches its end point, it is considered to be complete. 

8. What does the term "concordant readings" refer to?

Ans: Volumetric analysis measurements that vary by lesser than 0.05 mL are said to be concordant readings.

9. Why should a pipette never be held by its bulb?

Ans: The glass bulb could expand due to body heat, which would cause a measuring inaccuracy.

10. Why are burette and pipette rinsed using their solutions filled?

Ans: To get rid of anything that can stick to their edges and limit the amount of liquids they can hold, the burette and pipette are rinsed using the solutions they were loaded with.

Practical-Based Questions

1. What is the common name of solution in burette?

1. Analyte

2. Solvent

3. Titrant

4. None of the above

Ans: The solution used in the burette is the titrant.

2. What is the common name of the solution in a conical flask?

1. Analyte

2. Solvent

3. Titrant

4. None of the above

Ans: The solution used in the conical flask is analyte.

3. What is the unit of molarity?

1. M or Moles L-1

2. N or eq L-1

3. Mol per kg

4. None of the above option

Ans: The unit of molarity is M or Moles L-1.

4. Why rinsing a conical flask is not recommended?

1. Rinsing might cause the pipetted volume in conical flask to decrease

2. Rinsing might cause the pipetted volume in the conical flask to increase

3. Rinsing might cause the pipetted volume in the conical flask to precipitate

4. None of the three option

Ans: Rinsing might cause the pipetted volume in the conical flask to increase, hence it is not recommended.

5. What is the hydrochloric acid molar mass?

1. 34.5g

2. 35.5g

3. 36.5g

4. 37.5g

Ans: The hydrochloric acid molar mass is 36.5g.

6. What type of instrument is used in this experiment to add the last drop to avoid the extra drops in the solution while transferring the solution in a volumetric flask?

1. Dropper

2. Wash bottle

3. Pipette

4. None of the above three options

Ans: Pipette is used to avoid extra drops during solution preparation.

7. What type of acid is HCl?

1. Strong

2. Moderate

3. Weak

4. None of the above three options

Ans: HCl is a strong acid.

8. How much volume of H2SO4 is required for neutralization using phenolphthalein with 20mL of solution containing Na2CO3 and NaHCO3?

1. 5mL

2. 10mL

3. 15mL

4. 20mL

Ans: 10mL of H2SO4 is required for neutralization using phenolphthalein with 20mL of solution containing Na2CO3 and NaHCO3.

9. How is the strength of a particular solution determined?

1. Law of mass action

2. Equivalent law

3. Henry’s law

4. None of the three options

Ans: Equivalent law is used to determine the strength of a particular solution. 

10. How does distilled water act in chemical laboratories?

1. Indicator

2. Solvent 

3. Universal solvent

4. None of the three options

Ans: Distilled water acts as a universal solvent in chemical laboratories.

Conclusion

This chemistry experiment on the determination of strength and molarity of the given HCl solution with the given 0.05M Na2CO3 solution infers that the molarity of the given HCl solution is determined using the titration of given HCl against the 20mL of 0.05M Na2CO3 solution using methyl orange indicator.

It is prepared to utilize only pure chemicals, and standardisation can be done to determine the precise concentration. An acid-base titration technique centred on the back titration employing a standard base after the sample has dissolved in excess of standard acid.