Question: standardisation of hydrochloric acid with a standard solution of sodium...

Calculating the concentration of Na2CO3

Weight weighing bottle + Na2CO3 = 2.8510 g

Weight weighing bottle - Na2CO3 = 1.5250 g

Volume of volumetric flask for Na2CO3 solution = 250 mL

Calculating the concentration of HCl

Titration data:

Calculating the uncertainties

Absolute uncertainties:

Balance = ± 0.0002 g

Volumetric flask = ± 0.50 mL

Pipette = ± 0.05 mL

Burette = ± 0.05 mL

 

1.          Outline the steps involved for weighing by difference. Why is this important?

 

2.          Why should all solid be dissolved before transfer of the solution from the 250 mL beaker to the volumetric flask?

 

3.          Why is it necessary to thoroughly mix the solution after it has been made up to the mark?

 

Complete the following calculations using your provided sample data.

 

Part 1: Preparation of an approximately 0.05 mol/L standard solution of sodium carbonate

 

Weighings (g)
Weight weighing bottle + Na2CO3
Weight weighing bottle - Na2CO3
Difference = Weight Na2CO3

 

Calculate the specific concentration of sodium carbonate solution.

 

Concentration of standard sodium carbonate solution

 

mol L-1

Part 2: Titration of hydrochloric acid against sodium carbonate

 

Titrations

Burette Readings (mL)	Rough Titration	Accurate Titrations Place an asterisk (*) next to your concordant results
Final
Initial
Titre
Mean titre volume of your concordant results					mL

 

Mean titre volume of concordant results:______________mL

 

 

1.          Complete the boxes below with the names of chemical species present in each solution, and the quantities and units you know. For the unknown value put in a question mark.

 

 

Determining the concentration of hydrochloric acid

 

1.          Write the balanced chemical equation for the titration reaction.

 

2.          For which component in the titration are all values known? This is our known solution.

 

3.          For which component in the titration are some values missing? This is our unknown solution.

 

4.          For the known solution, what volume has been used and what is its concentration?

 

 

5.          Determine the number of moles of the known compound.

 

6.          At the endpoint, what is the molar ratio between HCl and Na₂CO₃?

7.          At the endpoint, how many moles of the unknown solution are present?

8.          What was the volume of the unknown solution that you used?

 

 

9.          Using your answers to Questions 7 and 8, what is the concentration of the unknown solution?

 

Uncertainty calculation

Hint! If you are having trouble with uncertainty calculations, refer to the Snapshot video on Blackboard or to the information provided on Page 13 (Principles of Measurement) of your laboratory manual.

Apparatus Used	Value	Absolute Uncertainty	Relative (%) Uncertainty
Balance for standard solution (g)
Volumetric flask for standard solution (mL)
Bulb pipette for titration (mL)
Burette for titration (mL)
Total % uncertainty

 

Remember that the final absolute uncertainty is determined by the equation:

 

                                     

Concentration of hydrochloric acid (with associated uncertainty)

 

±                                mol L-1

 

 

WITH SOLUTION AND EXPLANATION

DONT PLAGIARIZE...