Identifies and defines a question or problem and devices a practical procedure

My aim is to find out how much acid there is in a solution. I have been provided with a sample of sulphuric acid solution which has a concentration between 0.05 and 0.15 mol dm��. I will need to find its accurate concentration by carrying out a quantitative analysis known as titration.

> What is titration?

A titration is a quantitative analysis which can allow you to determine the precise end-point of a reaction. This is when two solutions are reacted together. One solution of known concentration is placed in the burette. The second solution is placed in the conical flask. An indicator is involved depending on how strong or weak the acid or alkali is. The solution in the burette is run into the conical flask just enough until the reaction is complete. This can be indicated by the change in appearance of the solution.

> Apparatus

* Beaker(s) (100cm�)

* Balance

* Spatula

* Anhydrous Sodium Carbonate (2.65g)

* Distilled Water

* Glass Rod

* Funnel

* Volumetric Flask (250cm�) (class B)

* Rubber or Plastic bung

* Burette (class B)

* White Tile

* Small Funnel

* Sulphuric Acid

* Conical Flask (250cm�) (class B)

* Pipette (25ml) (class B)

* Pipette Filter

* Methyl Orange Indicator

* Lab Coat

* Goggles

* Gloves

> Method

Making the Solution

* Direct Weighing Version

* Firstly, turn on the balance. Make sure the surface of the balance is clean.

* Place the empty beaker on the balance and record it’s mass.

* Press the Reset or Tare button. Now the balance should read zero.

* Use the spatula to carefully add 2.65g of Sodium Carbonate into the beaker. To carry out this procedure correctly, take reasonable amounts of Sodium Carbonate and then gently tap the spatula onto the side of the beaker to remove any excess Sodium Carbonate.

* When the reading is closer to the required value, use even smaller quantities. This procedure will be helpful to accurately measure the Sodium Carbonate.

* Now add some distilled water into the beaker to dissolve the Sodium Carbonate. Use the glass rod to crush large crystals until they become soluble. Add more distilled water if crystals are difficult to break.

* Make sure that the Sodium Carbonate has been thoroughly dissolved into the distilled water. Then use the distilled water to rinse out the glass rod while still inside the beaker. This will clear away any leftover sodium Carbonate on the glass rod.

* The Sodium Carbonate solution must be transferred from the 100ml beaker into a 250cm� (class B) volumetric flask.

* To do this accurately, place a funnel on top of the volumetric flask. Now carefully pour the Sodium Carbonate solution from the beaker into the volumetric flask. Hold the glass rod against the beaker for all of the solution to enter the volumetric flask and to prevent any spillage.

* When all of the Sodium Carbonate solution is in the volumetric flask, rinse the glass rod with distilled water above the funnel to wash away any leftover Sodium Carbonate. Furthermore, add more distilled water into the volumetric flask until reaching the graduation mark. Put the plastic or rubber bung on top and make sure its securely fastened to prevent any spillage.

* Now turn the volumetric flask upside down at an angle of 90� and bringing it back up with a smooth motion several times, to thoroughly mix the Sodium Carbonate solution.

Measuring the Solution

* The Sodium Carbonate solution in the volumetric flask will be measured to the required volume and will be carried out for the process of titration.

* I will be using a pipette filter and a 25ml pipette to remove the Sodium Carbonate solution from the volumetric flask.

* I will carefully insert the pipette which will be attached at the bottom end of the pipette filter. By giving a slight twist and a push, the pipette will be firmly secured in place.

* The pipette should contain Sodium Carbonate solution, 3ml greater than the required volume of 25ml.

* The pipette filter will be removed with care after a slight twist and immediately the index finger will be placed on top of the pipette to prevent the solution from falling below the graduation mark.

* To allow this solution to reach the graduation mark the index finger must be gently rubbed from side to side or top to bottom on the pipette.

* When the solution reaches the graduation mark which can be recognized by looking at the meniscus, the solution can be transferred from the pipette into a conical flask.

* The conical flask must be cleaned and rinsed with distilled water.

* The conical flask must be placed right next to the volumetric flask from which the solution was taken. This will reduce the risk of any spillage.

* Now let the solution of Sodium Carbonate from the pipette run into the conical flask until the last drop can be seen at the tip of the pipette.

* Gently touch the tip of pipette onto the side of the conical flask for that last drop to come out.

* Add 10 drops of methyl orange indicator into the conical flask.

Cleaning the Apparatus

* The burette itself must be cleaned with small quantities of distilled water. The burette should be held in a horizontal position and the water must be swirled around, to remove any leftover liquid from previous experiments.

* The distilled water should be drained from the burette through the open tap above a sink.

* In addition to this, Sulphuric Acid must be used in small volumes and the same procedure should be applied to remove any of the water droplets from the burette.

* The Sulphuric Acid solution should be drained from the burette through the open tap above a sink.

Adding Sulphuric Acid Solution into the Burette

* In a 100ml beaker add some Sulphuric Acid solution.

* Place a small funnel on the burette.

* Make sure the burette is below your head and you must not pour the solution if the burette is above your head. If it is then you must put the burette onto a stool when pouring the Sulphuric Acid solution.

* Ensure that the tap of the burette is closed when pouring the Sulphuric Acid solution. Hold the glass rod against the beaker so the acid solution only flows from the funnel and through the burette.

* Fill the burette to some extent above the 0ml but take care not to spill any of the acid solution. Now place the beaker which contains the acid solution under the tap and turn the tap open to get rid of the excess acid solution.

* Close the tap when the acid solution in burette reads “zero” by looking at the meniscus.

* Record the initial reading of the burette.

Titration

* Ensure that all the apparatus required for the process of titration has been thoroughly washed with distilled water and positioned in its correct place.

* The conical flask with Sodium Carbonate and methyl orange indicator must be placed onto a white tile on the burette stand.

* Make sure that the tap of the burette does not touch with the surface of conical flask.

* The tap of the burette must be cleaned with distilled water.

* The tip of the tap must be situated below the surface of the conical flask.

* To perform a rough titration the tap of the burette must be turned open to allow Sulphuric Acid solution to flow at a steady speed.

* At the same time the conical flask must be rapidly swirled around but making sure that it doesn’t bump into the tap.

* Look for any changes in the appearance of the Sodium Carbonate solution.

* When there is a change in colour, lower the flow of acid solution from the burette tap.

* The end-point is when the only few last drops are needed for the reaction to come to an end which can be recognised by the colour change of solution.

* As the end-point comes closer reduce the flow of acid solution to only allow few drops at a time.

* The reaction will come to an end which will be indicated by the change in colour of the solution inside conical flask.

* Close the tap of the burette.

* Wash down the sides of conical flask with distilled water to verify that the new colour appearance is real and does not fade away.

* Record the final reading of the burette.

* Write down the titre.

Accurate Titration

* When proceeding with an accurate titration it is mostly based upon some of the similar procedures carried out from the rough titration. However, particular attention is involved when achieving the end point of a titration.

* Accurate titrations will show correct results to some extent and are known to be concordant; meaning that they are within 0.1 of the other values.

* To perform an accurate titration prepare the burette with Sulphuric Acid solution and confirm that the meniscus reads “zero”.

* Record the initial reading of the burette.

* In a conical flask pipette 25ml of Sodium Carbonate solution and precisely add 10 drops of methyl orange indicator.

* Begin the titration by turning open and closing the tap of the burette to allow small volumes of Sulphuric Acid solution to flow through the burette and into the conical flask.

* Simultaneously, the conical flask must be rapidly swirled around in a smooth circular motion and making no contact with the tip of the burette.

* The tap of the burette must be handled with care as it will be turned ON and OFF quite a lot of times throughout the process of titration.

* When near to the end-point, lower the flow of Sulphuric Acid solution by varying the positioning of the tap on the burette and only allowing one or two drops at a time as it may affect the appearance of the solution.

* When even closer to the end-point, only allow one or even half a drop of acid solution into the conical flask.

* When there is a change in colour; close the tap of the burette.

* Clean the tip of the burette with distilled water.

* Wash down the sides of the conical flask with distilled water to clarify that the new colour appearance is real and does not fade away.

* Create a table and enter the set of results to 2 d.p. below the correct headings. Include the appropriate units and the experimental uncertainties.

11. b) Explains how the choice of procedures and/or equipment and/or

materials will ensure that the data collected is precise and reliable;

retrieves and evaluates information from multiple appropriate

sources; devices a risk assessment that is comprehensive, detailed

and relevant; produces a clear account using specialist vocabulary

appropriately and in which spelling, punctuation and grammar are

accurate.

> Experimental Errors

Volumetric Flask (Class B)

When a 250cm� volumetric flask is filled correctly. This will be indicated by the meniscus on the calibration line.

The error will be 0.2cm� or 0.08%

Burette (Class B)

One drop of burette has a volume of approximately 0.05cm�. The error of one drop in a volume of 50cm� gives a percentage error of 0.4%

Conical Flask (Class B)

When a 250cm� conical flask is filled correctly. This will be indicated by the meniscus on the calibration line.

The error will be 0.2cm� or 0.08%

Pipette (Class B)

When a 25cm� is pipette is used correctly it will have an error of 0.06cm� or 0.24%

Error � 100

Percentage Error =

Actual Reading

* In this experiment I will be using 2.65g of Sodium Carbonate.

It has an experimental error of �0.005g

0.005 � 100

Percentage Error =

2.65

Percentage Error = 0.189%

* Here is the calculation which shows the number of moles of Sodium Carbonate

Na2CO3 Na = 23 Ar � (2) = 46

C = 12 Ar = 12

O = 16 Ar � (3) = 48

46 + 12 + 48 = 106 Mr

Moles (mol) = Mass (g) � Molar Mass (Mr)

= 2.65 � 106

= 0.025 mol

* All of the apparatus which are involved in this experiment must be checked that they are not damaged, furthermore they will be thoroughly cleaned and rinsed with the distilled water to get rid of any dirt or unknown liquids. This will reduce the possibilities of experimental errors and will help in giving more accurate set of results.

* When making the solution of Sodium Carbonate it is important to add small quantities from the spatula as it will prevent the risk of exceeding over the required value. This method will be quite effective and reliable.

* When the Sodium Carbonate crystals have been thoroughly dissolved in the beaker, it is important to rinse out the glass rod in the beaker with some distilled water to wash away any leftover Sodium Carbonate.

* When transferring the Sodium Carbonate solution from the beaker into the volumetric flask, it is important to use a funnel and the particular pouring technique; this is when the glass rod is held against the beaker for the solution to flow straight into the burette. This procedure will prevent any spillage.

* When all of the Sodium Carbonate solution has been transferred into the volumetric flask, the funnel and the glass rod must be cleaned with distilled water to wash away any leftover Sodium Carbonate.

* The Sodium Carbonate solution in the volumetric flask must be turned upside down at an angle of 90� and then brought back up with a smooth motion, quite a few times. This will thoroughly mix the Sodium Carbonate and distilled water solution.

* The Sodium Carbonate solution in the volumetric flask must be measured with a 25ml pipette. This is because it has a very low fraction of error which is 0.06cm� or 0.24%

* The 25ml pipette must very carefully inserted into the pipette filter. For the reason that the pipette may snap and break.

* When taking some of the Sodium Carbonate solution from the volumetric flask it is important to always keep the tip of the pipette below the solution to prevent air bubbles which may flow through the pipette. This will be known as an experimental error and will cause inaccurate set of results.

* The pipette should contain Sodium Carbonate solution, 3ml greater than the required volume of 25ml. This allows a small boundary between the actual reading to prevent the volume of solution to fall below the actual reading when the pipette filter is removed.

* For the solution to reach the graduation mark, the index finger must be placed onto the pipette and moved gently from side to side and up and down. This procedure is very reliable and effective as it can precisely allow the solution to become level at the graduation mark which can be observed from the meniscus.

* When the solution of Sodium Carbonate is run from the pipette into the conical flask it is important that the conical flask must be placed close to the solution being transferred. This will prevent the solution from spilling.

* The last drop of Sodium Carbonate solution remaining in the pipette is as important as the rest of the solution therefore it must be released by touching the tip of the pipette onto the conical flask. This procedure will help to produce a set of accurate results.

* Methyl Orange Indicator has been in this experiment because this is titration which involves a strong acid and a weak alkali.

* When pouring the Sulphuric Acid solution into the burette it is important to use a funnel and to ensure that the burette is below your head. This is a safety precaution which can reduce accidents and prevent the acid solution from spilling.

* A white tile is to be found on the burette stand where the conical flask is placed and furthermore the white tile will help in identifying the change in colour of the reacted solution, during the process of titration.

* The tap of the burette must be cleaned with distilled water to get rid of any previous liquid. This will also improve the accuracy of the results.

* In titration the tap of the burette must be turned open and closed to allow small volumes of Sulphuric Acid solution to flow through the burette and into the conical flask. Large volumes of acid solution are not released as they will make it difficult to confirm the end-point and would create inaccurate results.

* Finally the sides of the conical flask must be washed down with distilled water to clarify that the new colour appearance is real and does not fade away.

Risk Assessment

> In this experiment I will be working with some important chemical solutions which are known to be acidic and alkali. In this investigation these are essential for the process of titration.

> These chemical solutions can be dangerous when not handled with the correct safety procedures. I will go through the potential hazards, the handing and storage conduct and the safety measures needed to prevent any minor or major accidents from occurring which might cause harm to the person carrying out this experiment.

* Sodium Carbonate Solution

* This solution was made from 2.65g of Anhydrous Sodium Carbonate which was added to some distilled water to make a solution.

Hazards

* Irritant-These substances are not corrosive but may cause reddening or

blistering of the skin.

* Corrosive-Substances which attack and destroy living tissues, including

eyes and skin.

* Harmful-Substances which are similar to toxic but are less dangerous.

Potential Health Issues

* Inhalation

Inhaling of sodium carbonate may cause irritation in the respiratory system. Symptoms of extreme inhalation will include coughing and difficulty in breathing. This may cause damage to the Nasal Septum.

* Ingestion

Sodium Carbonate is slightly toxic; however large quantities may be corrosive to the Gastro-Internal System where symptoms may include intense abdominal pain, vomiting, collapse and even death.

* Skin Contact

Severe contact may cause irritation with blistering and redness. The sodium carbonate solution may cause a lot of irritation or burns.

* Eye Contact

Contact with eyes may be corrosive and may cause Conjuctival Edema and Corneal Destruction. Other symptoms may appear from the absorption of sodium carbonate into the bloodstream via the eyes.

Handling and Storage

* Sodium Carbonate solution must be stored in a tightly stored container.

* It must be kept in a cool, dry and ventilated area.

* It must be protected from any physical damage.

* The containers of this certain solutions may still be hazardous when empty

as the chemical residue still remains.

* All warnings and precautions stated for this product must carefully be observed and followed.

In the event of an accident…

* The area must be ventilated.

* Sensible protective equipment must be used to clean up the spills.

* It is safe to vacuum or wet sweep that area to avoid dust dispersion.

Exposure Controls and Personal Protection

* Ventilation System

A local ventilation/exhaust system is recommended for the people to prevent low exposure as possible. It must control the emission and moreover preventing dispersions of this chemical into the working areas.

* Skin Protection

Protective gloves must be worn at all times when handling this chemical and furthermore comfortable clothing must also be worn.

* Eye Protection

Safety goggles must be worn at all times.

First Aid

* Eye or Skin Contact

In the case of contact, immediately wash eyes or skin with plenty of

water for at least 15 minutes. Remove contaminated clothing.

Seek medical attention immediately.

* Ingestion

If swallowed do not induce vomiting. Have large amounts of water and

seek immediate medical attention.

* Inhalation

If inhaled, go out in fresh air. Immediately seek medical attention if

having trouble in breathing.

* Sulphuric Acid Solution

* This solution is known to have a concentration between

0.05 and 0.15 mol dm�3

Hazards

* Corrosive-Substances which attack and destroy living tissues, including

eyes and skin.

* Harmful-Substances which are similar to toxic but are less dangerous.

Potential Health Issues

* Inhalation

The vapour is extremely irritant to the respiratory system. The fluid build

up on the lung may cause Pulmonary Edema and Gastro-Internal Track

The respiratory system can be affected from the acute exposure which may

cause tickling in the nose and throat, coughing and sneezing to

Bronchospasm which is asthma like effect.

* Ingestion

This will immediately cause damage to the Gastro-Internal Track.

Furthermore it may cause Haemorrhaging in the stomach or intestines.

Death may be caused from a large exposure to Sulphuric acid.

* Skin Contact

Sulphuric Acid can be corrosive to all tissues, including the skin, eyes,

and nose. Severe exposures can cause major and even fatal skin burns.

* Eye Contact

The eyes are particularly sensitive and blindness can result from contact.

May cause severe burns, prolonged pain and even permanent damage.

Handling and Storage

* Wear goggles, appropriate clothing and protective equipment when

handling Sulphuric Acid.

* Work in a ventilated area.

* When diluting ALWAYS add (ACID to WATER)

NOT (WATER to ACID)

* Avoid inhalation of highly concentrated mists.

* Store in a cool dry place.

* Keep away from combustible materials, reducing agents and strong bases.

In the event of an accident…

* The area must be evacuated.

* The fire department will isolate the area of spill.

* It will be restricted to prevent further leakage.

* The spill itself will be contained with dry earth, sand or other non-combustion material.

* Limestone will slowly be added to the spill to neutralise the acidic solution.

* The neutral solid material will be disposed off in appropriate containers.

Personal Protection

* Inhalation

Wear suitable breathing apparatus.

* Skin Protection

Protective gloves must be worn at all times when handling this chemical and furthermore comfortable clothing must also be worn.

* Eye Protection

Safety goggles must be worn at all times.

First Aid

* Eye Contact

In the case of contact with eyes, immediately flush eyes with

Running water for 15-30 minutes. Seek medical attention.

* Skin Contact

In the case of contact with skin, remove contaminated clothing.

Wash exposed area with large amounts of water for 15-30 minutes.

Gently wash the affect area with non-abrasive soap.

Use warm water if available. Seek medical attention.

* Inhalation

In the case of inhalation, use appropriate respiratory equipment to evacuate

the affected area. Go to a well ventilated area. If the person is not breathing,

perform artificial respiration and obtain immediate medical attention.

* Ingestion

In the case of ingestion, do not induce vomiting. If the person is conscious wash out mouth with water and give 2 or 3 glasses of water or milk to drink. Seek medical attention immediately.

* Methyl Orange Indicator

* For every separate titration 10 drops of methyl orange indicator will be added into the sodium carbonate solution for the process of titration.

Hazards

* Irritant-These substances are not corrosive but may cause reddening or

blistering of the skin.

* Harmful-Substances which are similar to toxic but are less dangerous.

Potential Health Issues

* Inhalation

May cause irritation in the respiratory system. Some of the symptoms include coughing, sore throat, laboured breathing and chest pains.

* Ingestion

May cause irritation in the Gastro-Internal Track. Symptoms include nausea, vomiting and diarrhoea.

* Skin Contact

May cause mild irritation and slight redness.

* Eye Contact

May cause mild irritation and slight redness.

Handling and Storage

* Methyl Orange Indicator must be stored in a tightly stored container.

* It must be kept in a cool, dry and ventilated area.

* It must be protected from any physical damage, direct sunlight and freezing.

* The containers of this certain solutions may still be hazardous when empty

as the chemical residue still remains.

* All warnings and precautions stated for this product must carefully be observed and followed.

In the event of an accident…

* The area of leak or spill must be ventilated.

* Sensible protective equipment must be used to clean up the spills.

* The liquid must be recovered to prevent any further damage.

* Collect liquid in an appropriate container or absorb with an insert materials.

E.g. Vermiculite or Dry Sand.

* Do not use combustible materials such as saw dust.

Exposure Controls and Personal Protection

* Ventilation System

A dilution ventilation is a satisfactory health hazard for this solution. In the case of discomfort to the worker a local exhaust system should be considered.

* Skin Protection

Protective gloves must be worn at all times when handling this chemical.

* Eye Protection

Safety goggles must be worn at all times.

First Aid

* Eye or Skin Contact

In the case of contact, immediately wash eyes or skin with plenty of  water for at least 15 minutes. Remove contaminated clothing.

Seek medical attention immediately.

* Ingestion

If swallowed do not induce vomiting. Have large amounts of water and  seek immediate medical attention.