A New Gravimetric Experiment, Lab Report Example

Abstract

The experiment is titled:  Conductimetric Titration and Gravimetric determination of BaSO₄ Precipitate.  The aim of this experiment is to determine the concentration of barium hydroxide and barium sulfate in a reaction. This experiment is founded upon the work of Hayden(1974) The precipitate will be ascertain by conductimetry and confirmation by mass in gravimetric titration.  The concentration of the bariumhydroxide solution will be ascertained. In addition the number of moles of barium sulfate as a precipitate will be explored. The amount of sulfuric acid and the molarity of the sulfuric acid is known.

Conductimetery and Gravimetric Titration of Barium Sulfate Precipitate

In this experiment there will be an observation of theconductive qualities during the reaction that occurs between H₂SO₄ and Ba (OH)².  This experiment will have the objective of ascertain the equivalence point.  This information will be applied in order to derive the concentration of the Ba (OH)²solution.  There is an insoluble product that is a yield from the reaction between barium hydroxide and sulfuric acid.   The other products are barium sulfate and water.  The reaction is demonstrated as:

Ba²⁺(aqueous) +  2 (OH)^2- + SO₄ ^-2  ( aqueous) ? BaSO₄ + H₂O (l).

In this chemical reaction, the comprehensive number of dissolute ions in the solution is diminished drastically during the chemical reaction as a solute is formed.  Considering that 0.100 M H₂SO₄ is gradually aggregated to aBa (OH)² (aqueous ) with an indeterminate concentration, the modifications in the conductive qualities will be examined by means of the application of a conductivity probe.  In the instance that the probe is inserted into a solution that possesses ions and the solution is conductive to electricity, a complete electrical circuit is formed through the solution with the electrodes that are inserted on the lateral aspects of the body of the probe.

his action has the outcome of producing a conductivity rating that can be interpretedby the interface.  The units of electrical conductivity that will be applied are the micro siemens per cm ( ?S/ cm).  Furthermore , the precipitate will be recuperated and the mass of the solute will be ascertained.  IN this experiment, two methods will be applied in order to determine the molar concentration of the barium hydroxide that is suspended in water that is placed in a titration process with H₂SO₄ that has a known concentration

Objectives

The goals of this experiment are to assess the conductivity of the chemical reaction between H₂SO₄  and  Ba (OH)^2.  The values that are derived as conductivity values will be applied in order to ascertain the equivalence  value of the reaction.  The weight of the solute will be applied in order to determine the equivalence value of the reaction from a gravimetricperspective.  The number of moles in the Ba (OH)² ( aq) will be calculated,.

Procedure

The Vernier drop counting device will be applied in order to obtain the volumereading.  The titrant H₂SO₄ will be inserted one drop at a time .  The drops will flow from the reagent reservoir down to the drop counting slot.  Subsequent to the drops reaction with the reagent that is in the flask, the volume of the drop will be computed and the conductivityvolume information pair will be docuiment4ed.

Materials

1. Goggles
2. 10 ml graduate
3. 60 ml reagent reservoir
4. Vernier drop counting device
5. 100 ml flask

Procedure

1. Establish the selector control on the conduction probe to the range of 0- 20,000 ?S/cm. Attach the conduction probe to the Lab Quest and select new on the menu.
2. Establish the conductivity probing device and the drop counting device
3. Descend the drop counting device on the ring stand and attach to DIG 1.
4. Acquire the 60 ml reservoir for the reagent. Ensure that the valves are closed by turning them to the horizontal settings.
5. Assess approximately 60 ml of 0.100 M H₂SO₄ into a flask that has a 250 ml capacity.  Evaluate and documentthe molarity of the H₂SO₄  (aq).
6. Establish the ring stand , burette and flask in order to perform the titration. Rinse the flask and fill with the H₂SO₄ (aq).
7. Apply a utility clamping order to attach the conduction probe to the ruing stand. The conduction probe should be positioned in the Ba (OH)(aq) in a manner where it does not interfere with the stirring rod.
8. Position the flask that contained the H₂SO₄ (aq). Under the point of the reservoir.
9. Evacuate a small quantity of the H₂SO₄ (aq).into the flask in order that the reservoir’s tip appears to be filled. In order to achieve this , the valves must be turned vertically for an instance and returned to the horizontal position.  Insert the H₂SO₄ (aq).  into the flask
10. Adjust the drop counting device in order that an exact amount of H₂SO₄ (aq). Titrant is evaluated in ml.  Select calibrate from the menu .  Place the setting on drop counter.  Choose equation.   Place the values for the new intercept and the new slope.  Choose OK  and go straight to step 6.  In order to conduct a novelcalibration, choose start and continue with this step.  Position a 10 ml graduate under the slot of the drop counting machine , aligning it with the reservoirfor the reagent.  Release the lower valve of the reagent reservoir by placing  it in a vertical position.  Gradually release the upper valve of the reservoir for the reagent in order to release one drop every two seconds.  The drops will demonstrate a count on the screen.   As the volume of the H₂SO₄ (aq).  attains 9- 10 ml., stop the flow from the reagent reservoir.  Document the number of drops for future usage and choose OK.
11. Assemble the conductivity profiling device. Put the magnetic stirrer on the ring stand’s base.  Position the conduction probe through the aperture in the drop counting device.  Connect the micro stirrer to the lower part of the PH sensing device.  Turn the paddle wheels of the micro stirrer and ensure that they do not make contact with the conduction probe.  Modify the position of the reagent reservoir and the drop counting device in order to ensure alignment with the central part of the magnetic stirrer.  Raise the connection probe and insert the beaker that possesses the Ba (OH)² (aq) on the magneticstirrer.  Descend the conductivity into the flask.  Modify the position of the reagent reservoir in order to position below the aperture of the drop counting device.

Titration

1. Initiate the data collection process. The first drop must enter through the drop counteraperture in order to begin collecting data.   Release the lower valve.  The upper valve should be modified to a flow rate of one drop per two seconds.  As the first drops are going through the drop counter´s aperture,  review the graph in order to ensure that the initial data pair was documented.  Note that the conductivity measurements decrease gradually.  View the graph and coordinate when the conduction increases.  This will be the point of the equivalence value of the reaction.  As the conduction increases , allow a few more ml of titrant H₂SO₄ (aq).  Cease the data collection in order to examine the graph of conductivity in comparison to volume.  Close the reagent valve.
2. Review the data that is one the displayed graph in order to determine the equivalence point. In order to review the data pairs on the graph any position is selected.  The H₂SO₄ (aq) volume is recorded in conjunction with the position of minimal conductivity 100 ?S.  The information is placed on a table.
3. Filter and assess the weight of the BaSO₄ solute . Apply a hot plate in order to heat the beakerof the BaSO₄ (aq).  Apply heat to raise the solution to its point of ebullition.  As the mixture is nearing the point of ebullition, place the ring stand and filter in position.  Assess and document the mass of the filtration paper .  Place the filter in the funnel.  Let the mixture cool, then pass the mixture through the filter.  The solute should be desiccate in an oven for 15 minutes.  Allow the solute to cool.  Assess and documentthat mass of the solute and the filter paper.
4. Wash the conductivity probe in distilled H₂
5. Retrieve the data from Lab Quest.

Repeat the process if necessary.  Document the outcomes in a data table

Data Table

Calculations

Equation

M= m/n, Molar mass = M/ N.

Percentage error = {experimental value – actual value)/ actual value X 100

1. 5 mL/ 1L/ 0.100 M = 1.95 X 10 ^-3 M
2. Mol H₂SO₄  = Ba (OH)²

1.95 X 10 ^-3 M / 0.100 L = 0.0195M

3. 0.505 g Ba SO₄ /233.43g/ mol Barium Sulfate = 0.00216338945M BaSO₄
4. Ba(OH)² = 0.00216338945M BaSO₄ / 0.100L = 0.021633895 % concentration.
5.  (0.0195- 0.02163)/ 0.02163 = ±9.847 % errorfor Barium Sulfate,

0.0195- 0.100)/ 0.1.00 = ±8.05% error for equivalence point.

Discussion

The laboratory experiment attempted to ascertain the concentration of Ba (OH)² by conductimetric experiment in order to ascertain the equivalence point of Ba (OH)²by performing a gravimetric determination between barium hydroxide and hydrogen sulphate. The molarity at the equivalence point was determined to be 0.0195 M with a percentage of error 8.05%. The molarity that was determined was 0.02163M. The potential sources of error could be air bubbles. A second potential source of error could be attributed to the premise of barium sulphate being a colloid and its low characteristic of solubility.

References

Hayden, D. (1974). A new gravimeteric experiment for general chemistry. J. Chem Educa, 51(12): 783.

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