Determination of conductance of a strong acid And Weak acid (HCl)
Table of Contents
Chemicals Required:
The chemicals required are:
- Acetic Acid
- Hydro Chloric Acid
- Distilled water
Glassware:
Required Glasswares:
- 2 Measuring Flask(100 ml)
- 2 Beakers(100&250 ml)
- A Pipette (10ml)
- A Measuring cylinder (50 ml)
Apparatus:
Required apparatus:
- A Conductivity meter
- An Electrical Balance
- Iron Stand
- Clamp
Theory:
Conductance is an expression of these ions due to which current flows through a substance. Conductance is shown by an upper case letter “G”.
The reciprocal of resistance is called conductance.
Conductance= 1/Resistance
The units used for conductance are ohm-1 or mho. Its unit is also known as Siemens.
Siemens:
It can be defined as:
If a current of one ampere passes through a conductor/ mixture across which a voltage of one volt exists then conductance is known as one Siemens.
Factors of Conductance:
The conductance of solution is due to:
- Number of ions
- Movements of ions
In general, when the applied voltage is held constant, the current In a DC is directly proportional to the conductance. When the numbers of ions increase the conductance due to ions also increases.
Conductivity meter:
An electrical conductivity meter measures the electrical conductivity in a solution in ionic forms. Basically, movements of ions produce the conduction. The conductivity meter has two modes.
- Conductance mode
- Resistance mode
Conductometry is often applied to determine the total conductance of a solution or to analyze the endpoint of titration that includes ions. A conductivity meter or Conductometry has a sensor in the electrodes that measure the conductance.
Determination of conductance of a strong acid And Weak acid (HCl)
Principle:
Conductivity meter which measures the conductivity, two plates are placed in the sample solution and a potential is applied across the plates i.e. normally a sine wave voltage, and the current that passes through the solution is measured.
Calibrations of conductivity meter:
There are some manufacturing faults in equipment which lead to wrong readings and further calculations.
So calibration is required for correct and accurate readings. Following steps are necessary to calibrate a conductivity meter, which is easy and standardized:
- The conductivity meter usually contains a menu item that allows to enter the calibration mode
- Change the setting on the side that can be adjusted with a small screwdriver or tool
- Now place the probe in a solution of known conductivity value and temperature and set the meter to that conductivity
Procedure:
- Glassware which was used in this experiment was washed with detergents to remove the impurities and rinsed first with tap water then with distilled water and dried properly
- Solutions of different concentrations of HCl and CH3COOH were prepared
- Conductometer was calibrated by dipping its electrode in distilled water. It was managed at conductance mode
- First of all the conductance of different concentrations of weak electrolyte i.e. CH3COOH was measured
- For this purpose 50ml of CH3COOH solution of 0.1M was taken in a beaker and an electrode of Conductometer was dipped in it and noticed the readings
- The same procedure was repeated for all concentrations of CH3COOH required for the experiment
- Now the conductance of HCl solutions of all concentrations was found one by one
- All readings were taken separately
Determination of conductance of a strong acid And Weak acid (HCl)
Observations and calculations:
Solution preparation:
Required concentrations of weak electrolyte
(CH3COOH)
Required concentrations of CH3COOH
- C1=0.1M
- C2=0.2M
- C3=0.3M
- C4=0.4M
- C5=0.5M
Required Weight =molarity× molecular weight×
Amount of compound = V/1000
Amount of compound = 0.1 × 60 × 100 /1000
Amount of compound = 0.6 g
Basically, acetic acid (CH3COOH) is available in solution form or liquid form. So we need to find out the volume.
Density of acetic acid = 1.05 g cm-3
Purity of acetic acid = 100%
Required Volume = Mass / Density
Required Volume = 60 / 1.05
Required Volume = 57.14 ml
So we need the volume for 0.6 g
As we know
60 g of acetic acid contains by volume = 57.14 ml
1 g of acetic acid contains by volume = 57.14 ml / 60
0.6g of acetic acid contains by volume =57.14 ml/60 × 0.6
= 0.6 ml
Because acetic acid is 100% pure so 0.6 ml of acetic acid was taken from the reagent bottle with the help of a measuring cylinder and poured into a 100 ml measuring flask and diluted with distilled water up to the mark.
Similarly, all required concentrations were prepared with the same procedure.
Required concentrations of strong electrolyte
(HCl)
C1=0.1M
C2=0.2M
C3=0.3M
C4=0.4M
C5=0.5M
Concentrations of (HCl)
C1
Percentage purity of HCl=31.5%
Density of HCl=1.16g/cm3
Amount of HCl in 1M solution in 1000ml=36.5g
Amount of HCl in 1M solution in 1ml=36.5/1000 g
Amount of HCl in 1M solution in 100ml=36.5×100/1000g
Amount of HCl in 0.1M solution in 100ml=3.65×0.1g
=0.365g
HCl is always available in solution form, so we have to find the volume of HCl.
Volume= Mass/Density
= 0.365/1.16
= 0.314ml
As solution of HCl is not 100% so further calculations must be carried out
Purity of HCl solution= 31.5%
So
31.5ml of HCl are present in = 100l
1ml of HCl is present in = 100/31.5ml
0.314ml of HCl is present in = 100×0.314/51.5ml
= 0.99ml = 1ml
So 1ml of HCl was taken with the help of a measuring cylinder and poured into a 100ml measuring flask and then filled the flask with distilled water up to the mark.
Similarly, all required concentrations were formed in a similar way.
Conductance of CH3COOH
Sr.no | Concentration | Conductance (Siemens) |
1 | O.1 | 1.5×104 |
2 | O.2 | 1.6×104 |
3 | 0.3 | 1.7×104 |
4 | 0.4 | 1.9×104 |
5 | 0.5 | 2.1×104 |
Conductance of HCl
Sr.no | Concentration (M) | Conductance (Siemens) |
1 | O.1 | 2.1×104 |
2 | O.2 | 2.3×104 |
3 | O.3 | 2.5×104 |
4 | O.4 | 2.8×104 |
5 | O.5 | 3.1×104 |
Result:
The conductance of a strong electrolyte is greater than the conductance of a weak electrolyte with a respective concentration.
The conductance increases with an increase in the molarity of an electrolyte.
Precautions:
- Make solutions carefully because both acids can burn the skin if spit
- Do not use tap water while making solutions of different concentration because tap water contains different ions which affects the concentrations, always use distilled water
- Try to use a little number of chemicals and perform the experiment at lower concentrations
- Avoid eating and drinking activities during lab performance
- Gloves and glasses are necessary during lab experiments
- Avoid horseplay during a lab experiment
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