Chemistry EEI

Chemistry EEI: In the Mix

1.0) Abstract

The aim of the extended experimental investigation was to validate the original masses of the different compounds presented in a mixture. These substances are unique in terms of their physical and chemical properties. Therefore, in order to separate the mixture into its original components, specific methods of separation were utilised to gain the most accurate results. It was hypothesised that, based on the background information presented and previous research, each substance within the mixture will be able to be separated and the amount of each substance will be revealed by using certain physical and chemical separation techniques. In carrying out correct procedure and chemical calculations; the amounts of each substance will be found. The initial and final masses of each substance where as follows:

* Hexane - Initial: 13mL Final: 12.5ml

* Ethanol - Initial: 25mL Final: 22mL

* Sand - Initial: 5.5g Final: 5.206g

* Iron - Initial: 2.4g Final: 2.575g

* Na2SO4 - Initial: 0.6g Final: 0.564g

* NaCl - Initial: 1.3g Final: 1.636g

The results showed that the major findings of this report generally supported the hypothesis in that fairly accurate final measurements generally matched initial measurements. However some major discrepancies in results included NaCl and Iron. NaCl finial measurement was greater than the initial because of the fact that it was weighed after only a short period of time after the reaction and therefore was not completely dry. This made the AgCl(s) heavier than it was, altering calculations and ultimately varying the final measurement. The Iron final measurement was slightly greater than the initial because the iron was left to dry over an extended period of time, thus allowing the formation of hydrated oxide and ultimately rust to form on the iron fillings. This ultimately increased the weight when weighed. The set procedure however was established based on the specific chemical and physical properties of each substance in the mixture. The most effective method of separation was utilised in the correct sequencing in order to achieve most accurate results.

2.0) Introduction and background

The purpose of the extended experimental investigation was to take a mixture, (two or more different substances mixed together but not combined chemically), of several individually unique substances, (in terms of the states of matter and the physical and chemical properties), and undergo a specific set order of physical and chemical separation processes. The objective of this was to validate the original masses of the different compounds of the original mixture.

The mixture included a number of different substances, either in their solid or aqueous states. The mixture compositions included:

* 5.5 g of sand

* 2.4 g of Iron fillings

* Water (in excess)

* 25 mL of Methylated Spirits

* 1.3 g of NaCl

* 0.6 g of Na2S04

* 13 mL of Hexane (Vegetable oil to be used to represent hexane)

In order to separate the mixture into its original compounds, a number of physical and chemical separation methods must be utilised based on the unique physical and chemical properties of each component. Using a flow chart, the technique of separation used was determined.

2.1) Flow chart

2.2) Decanting

In order to determine these specific techniques of separation, the properties of each substance was studied to determine as to why these methods of separation could be used.

Decanting is the process of carefully pouring the top layer of two immiscible substances. In the case of decanting Hexane and water; the Hexane a non-polar substance, H2O is the polar substance, therefore the two substances are immiscible.

Hexane is a non polar covalent compound. A non polar covalent-compound includes bonds in which electrons are unequally shared between elements having a difference in electro negativity of less than 0.5. (Lefers, 2004).When atoms of similar electro negativity share electrons, to form a covalent compound, the shared electrons tend to be evenly controlled by both atoms. The resulting bond is evenly charged on all sides and is said to be a pure non-polar covalent bond (Lefers, 2004). However, Polar covalent bonds, e.g. (H20) involve the unequal sharing of electrons between two atoms. The electrons are pulled toward the more electronegative element. This will result in a slight - charge on that atom and a slight + charge on the other atom. The slight charge is represented as δ+ or δ-. Whether a molecule is polar depends on the electro negativity of atoms in the covalent bond and the shape of the molecule.

Hexane's chemical formula is C6H14.

Referring to Hexanes structure in 2, the structure is evenly charged on all sides. Hexane is a linear alkane Hydrocarbon, which is an organic compound consisting of entirely hydrogen and carbon atoms (Helmenstine, 2009). These atoms are linked together exclusively by single bonds. Hexanes electrons are evenly shared throughout the molecule. Non polar molecules are only miscible in other non polar substances. Therefore hexane does not dissolve in water. Due to the lower density of hexane compared to water, the hexane forms the top layer and this is why the hexane and water can be separated using decanting and a separation funnel.

Water has the specific chemical structure to be able to form two hydrogen bonds. This is the ideal number because it has no extra lone electron pairs, also called ‘hydrogen acceptors'. This allows water to form a dense, ring like configuration. However, Hydrogen has many ‘hydrogen acceptors', and therefore its chemical structure does not allow it to be as tightly compacted as water due to its weaker inter molecular forces. This prevents the two liquids from forming a homogeneous mixture and instead the immiscible liquids separate into two distinct layers (Smith, 2006).This allows the two liquids to be separated be a separating funnel.

A separating funnel is a pear- shaped piece of apparatus that tapers to a narrow tube just above the stopcock. This shape allows the more dense liquid to run out the bottom without getting it contaminated with any of the top substance.

2.3) Filtration

File:Silica.svgIn order to separate the solids, (Iron and Sand), from the liquid mixture, filtration was used. Filtration is a technique used to isolate an organic solid. (Feist 2000) The liquid or solution passes through the filter paper, (as the filtrate), while the solids remain on top of the filter paper.

The reason sand is insoluble in water is because sand in a non polar substance. This is because sands chemical structure, (Silicon Dioxide, Si02) has extensive covalent bonding which is called a covalent lattice; as apparent in 4. Covalent bonds are the strongest bonds and therefore can not be broken apart by water. The silicon is more attracted to the oxygen than it is to the hydrogen therefore this does not allow sand to be soluble in water.

Solids retain a fixed volume and shape. They are rigid and the particles are locked into place. They are not easily compressed and there is little free space between particles. The rigid particles of a solid can not move/ slide past each other, therefore constrict the object from flowing. However liquids assume the shape of part of the container which it occupies. Unlike solids, particles can move/slide past one another. Liquids are also not easily compressed and like solids have little free space between particles. However, liquids flow easily and its particles can move/ slide past one another. These differences in properties of solids and liquids allow filtration to be an affective separation method.

2.4) Magnetic separation

Iron is a metal and consists of an orderly three dimensional array of positive ions held together by a mobile ‘sea' of delocalized electrons. The valence electrons break away from their atoms, leaving behind positive ions. The free electrons no longer belong to a particular atom, move randomly though the lattice and, by being shared by numerous positive ions, provide the chemical bonding that holds the crystal together.

Once the sand and iron are separated from the mixture, magnetic separation can be used in order to separate the two solids.

Iron is considered ferromagnetic which means it is strongly attracted to a magnet. Iron has large magnetic moments due to un-paired electrons in its outer orbitals. There must be three or more unpaired electrons in an element's outer orbital's to create ferromagnetisms. Iron has 4 unpaired electrons in its 3d orbital which gives iron its distinct magnetic characteristics. The un-paired orbitals in Irons chemical structure are represented by the red electrons in the 3d orbitals in 4.

The reason as to why Iron is magnetic is because of its Magnetic Domains. These are forces in neighboring atoms which are held parallel by quantum mechanical forces (Hoadly, 2008). These atoms with these magnetic characteristics are grouped into regions called domains, evident in 5.(Hoadly, 2008). Each domain has its own North and South Pole. Each individual domain is the smallest known permanent magnet and is composed of approximately one quadrillion (10 to the 15) atoms (Hoadly, 2008).

In un-magnetized ferromagnetic materials, the domains are randomly oriental and neutralize each other. The result is that there is no single North Pole or South Pole. However, the magnetic fields are still present within the element (Hoadly, 2008). The application of an external magnetic field causes the magnetism in the domain to become aligned so that the magnetic forces are added to each other and lined up with the applied field as manifested in 5.

Irons domains as a stronger external magnetic field is applied

Addition of Magnetic Field to the Iron

Subtraction of a Magnetic Field to the Iron

Iron is known as a soft magnetic material. Small external fields will cause a great amount of alignment in soft magnetic material. However, due to the small restraining force, only a little of the alignment will be retained when the external field is removed (Hoadly2008).

Sand however, does not have these specific magnetic properties and when an external magnetic force is applied to the mixture, the sand will not be attracted to the magnet.

2.5) Fractal distillation

In order to separate the methylated spirits from the remaining mixture, fractal distillation must be used. Fractal distillation is a physical process used to separate mixtures that contain at least one liquid (in this case two). Fractal Distillation works because each substance in the mixture has its own unique boiling point. So, as a mixture is heated, the temperature of the mixture rises until it reaches the temperature of the lowest boiling substance in the mixture. The more volatile substance will then evaporate and condense a number of times in order to ensure only one substance is being evaporated as the two liquids may have similar boiling points. Meanwhile, the other components of the mixture remain in their original phase until the lowest boiling component has all boiled off completely, at which point the temperature will again start to rise above that liquids boiling point. Once the more volatile substance has been evaporated, the gas state of the substance will then be cool and turned back into its original aqueous solution and collected in a separate container as the distillate.

Methylated spirits is a mixture of 95% ethanol and 5% methanol. Ethanol's chemical formula is C2H5OH and is miscible with water (Eddleman, 1987). Its boiling point is 78.5 degrees, therefore less than water and this is the reason these two substances are able to be separated by fractal distillation. Methanol's chemical formula is CH3OH and is boiling point is 64.6 deg C and its melting point is -97 deg C (Dunk, 2001).

The reason water and ethanol are able to be separated by means of fractal distillation is because of the hydrogen bonging of both water and ethanol. Hydrogen bonds result from the electrostatic attraction between the slight positive charge on the Hydrogen and the partial negative charge on the Oxygen, Nitrogen or Fluorine.

Therefore it takes more energy to break water molecules apart compared to ethanol because of its opportunity for hydrogen bonding. As apparent in 7, there are two polar covalent bonds within the molecule. As apparent in 8, there is only one polar covalent bond which is the reason as to why it has a lower boiling point of 78.5 degrees as apposed to waters boiling point of 100 degrees. The more opportunity that a substance has for hydrogen bonding, the more energy required to bring an aqueous solution to a boil, therefore the higher boiling point and.

2.6) Precipitaiton reactions

The remaining mixture contains 1.3 g of NaCl and 0.6 g of Na2SO4 and H20. In order to calculate the amounts of each, chemical separation techniques must be used. In order to be able to calculate the initial concentrations of NaCl and Na2S04, Barium Nitrate Ba(NO3) and Sliver Nitrate Ag(NO3) must be added. In order to separate these substances, a precipitation reaction must take place, where a reactant is added to form an insoluble product. The reactants must satisfy the required properties in order to successfully precipitate the substance. The reactants must form a double displacement reaction, where one of the products is insoluble. The other product will always be soluble in this case because the sodium ion will always form a soluble compound. The reactant itself must also be soluble, which can be achieved by having a nitrate as the reactant because nitrates are always soluble. The reactant which will be used to precipitate the Na2SO4 will be Barium Nitrate. The molecular formula for this reaction is:

Barium nitrate Calculation

Ba(NO3)2 + Na2SO4 ↔ BaSO4 + Na2NO3

When the Ba(NO3)2is added to the Na2SO4, the cation of the barium and the anion of the Na2SO4 will have a stronger attraction for each other than the attraction Ba has for NO3 and S04 has for Na2 therefore forming BaSO4 and Na2NO3. The NO3- anion and the Na2 cation are both soluble and the BaSO4 is insoluble in water and therefore can be filtrated out of the solution. The Ba(NO3)2 was added first because it enabled all of the Na2SO4 to be precipitated without any of the Ba(NO3)2 reacting with Na2SO4 (the bi product of reacting Ag(NO3)2 + NaCl).

The reactant which will be used to precipitate the NaCl will be Ag(NO3). The molecular formula for this reaction is:

Silver Nitrate Calculation

Ag(NO3)2 + NaCl ↔ AgCl + Na2NO3

When the Ag(NO3)2 Is added to the NaCl, the cation of the silver nitrate and the anion of the NaCl will have a stronger attraction to each other than the attraction Ag has with NO3 and Na has with the Cl. The reaction will then be AgCl(S) + Na2NO3(aq). The reason for this is because the Cl- anion usually is a soluble anion; however an exception occurs when it is chemically bonded with Ag+ cation. Therefore it becomes a solid and forms a precipitate. AgCl is insoluble because it has greater attraction to each other than it does for water. Therefore water is unable to break AgCl apart. The NO3- anion is a soluble anion Na2+ is a soluble cation; therefore when the two become chemically bonded, the compound becomes soluble in water.

The AgCl and the BaSO4 can then be weighed and calculations can be made to find the original amount of NaCl and Na2SO4 that was present in the mixture.

It is hypothesised that, based on the background information presented and previous research, each substance within the mixture will be able to be separated and the amount of each substance will be revealed by using certain physical and chemical separation techniques. In carrying out correct procedure and chemical calculations; the amounts of each substance will be found.

3.0) Apparatus

• 2 x 250ml beakers

• 1 x 600ml beaker

• 1 x conical flask

• 1 x Filter Paper

• 1 x Permanent Magnet

• 1 x Funnel

• 1 x Separating Funnel

• 1 x 0.5M Barium Nitrate

• 1 x 0.1M Silver Nitrate

• 1 x Fractional Distillation Equipment

• 2 x 25ml Measuring Cylinders

3.1) procedure

Decanting

1) Mixture was poured into beaker until remaining solution contained a small amount of liquid.

Filtration

1) The funnel was situated on the retort stand, exactly over a 250ml beaker filter paper was then lined at the mouth of the funnel.

2) Water was added to the sand and iron, to ensure that all soluble residues were dissolved properly so it would pass through the filter paper.

3) The sand and iron mix was slowly poured onto the filter paper lined funnel, ensuring that there was no overflow.

4) Once all of the mixture was filtered, the liquid in the beaker was poured into the 600ml beaker which already contained the remainder of the mixture.

5) The sand and iron was kept on the filter paper, and placed on a watch glass to dry, in preparation for magnetic separation.

Separating Funnel

1) The Decanted mixture was decanted into the separating funnel and allowed to settle.

2) Once settled stop cock was turned to allow flow of mixture into a beaker.

3) Once mixture was poured out and collected, stop cock was turned again to stop flow and trap Oil.

4) Stop cock was then turned to allow flow of Oil into separate beaker.

Magnetic Separation

1) Magnet was placed in plastic bag to ensure that no substances could attach to magnet and could be easily removed.

2) Sand and Iron were distributed evenly over the filter paper.

3) Magnet was used to separate the Iron from the sand.

4) The Iron was then placed into a plastic bag.

5) The watch glass was weighed and recorded.

6) Iron was weighed on watch glass and recorded.

7) Sand was weighed on watch glass and recorded.

8) Iron and sand were then placed into separate containers.

Fractional Distillation

1) The mixture was filled into the distillation flask to a ½ to ¾ of its capacity.

2) Boiling chips were then added to the liquid before heating commenced.

3) Fractional Column was connected to distillation flask.

4) Distilling adapter was connected to distillation flask, water condenser and thermometer.

5) Receiving flask was then placed under condenser in order to collect substances.

6) Once Set up heat was applied to distillation flask by turning the distillation adapter on.

7) A beaker was set up in order to collect waste.

8) Temperature was monitored until it remained at a constant temperature.

9) Beaker was then removed and measuring cylinder was placed in order to collect distillate.

10) Thermometer was monitored until temperature started to increase.

11) Distilling adapter was then turned off and set up allowed cooling.

12) Substances results were then recorded

Precipitation NaCl

1) Filter paper was weighed.

2) A retort stand was set up with a separating funnel.

3) Filter paper was placed inside the separating funnel.

4) Beaker was set up in order to contain mixture sieved through separation funnel.

5) 23 mL of silver Nitrate was added to solution in a beaker.

6) Mixture was then poured into the separating funnel.

7) The mixture was given time to settle.

8) Filter paper containing AgCl was then weighed.

9) Results were recorded.

Precipitation Na2SO4

1) Filter paper was weighed.

2) A retort stand was set up with a separating funnel.

3) Filter paper was placed inside the separating funnel.

4) Beaker was set up in order to contain mixture sieved through separation funnel.

5) 18mL of barium nitrate was added to solution in beaker and given time to settle.

6) Solution was then poured into separating funnel and allowed time to separate mixtures.

7) Filter paper containing BaSO4 was then weighed.

8) Results were recorded.

4.0) results
Table 1:

Original and Initial Masses of the Different Compounds of the Original Mixture.

Substance

Initial Measurement

Final Measurement

%Difference

Hexane (Oil)

13mL

12.5mL

-3.85%

Ethanol

25mL

22mL

-12%

Sand

5.5g

5.206g

-5.35%

Iron

2.4g

2.575g

7.29%

Na2SO4

0.6g

0.564g

-6%

NaCl

1.3g

1.636g

25.85%

5.0) calculations

Volume to be added for precipitation reactions:
Barium Nitrate Calculation

Ba(NO3)2 + Na2SO4 = BaSO4 + Na2NO3

0.25M of Ba(NO3)2

0.6g of Na2SO4

n=m / mm

n=0.6 / 45.98 + 32.07 + 64

n=0.004224

c= n / v

v=n / c

v=0.004224 / 0.25

v=16.896mL

Therefore 16.896mL of Ba(NO3)2 will be added to the solution to precipitate BaSO4.
Silver Nitrate Calculation:

Ag(NO3)2 + NaCl = AgCl + Na2NO3

0.5M of AgNO3

1.3g of NaCl

n=m / mm

n=1.3 / 22.9 + 35.45

n=0.0222

c=n / v

v=n / c

v=0.0222 / 0.1

v=22.3mL

Therefore 22.3mL of Silver Nitrate will be added to the solution in order to precipitate AgCl.
Na2SO4 Calculations: Mass of initial ionic compound calculations.

Na2SO4 + Ba(NO3)2 = 2NaNO3 + BaSO4

1M BaSO4 produced from 1M Na2SO4

1:1

BaSO4=m / mm

= 0.926/233.4

= 0.00397M

If 0.00397M BaSO4 precipitated, 0.00397M Na2SO4 initially

n Na2SO4= 0.00397

m Na2SO4= n * mm

= 0.00397 * 142

= 0.564g

0.0564g Na2SO4 initially present.
NaCl Calculations

NaCl + Ag(NO3)2 = AgCl + 2NaNO3 + BaSO4

1M AgCl produced from 1M NaCl

1:1

AgCl=m / mm

=4.015 / 107.87 + 35.45

=0.028

If 0.028M AgCl precipitated, 0.028M NaCl initially

n NaCl=0.028

m NaCl=n * mm

=0.028 * (22.99 + 35.45)

=1.636g

1.636g NaCl initially present

6.0) Discussion

The aim of the extended experimental investigation was to take a mixture of several individually unique substances and undertake a detailed set order of physical and chemical separation processes. The purpose of this was to authenticate the original masses of the singular compounds of the original mixture. It was then hypothesised that, based on the background information presented and previous research, each substance within the mixture will be able to be separated and the amount of each substance will be revealed by using certain physical and chemical separation techniques. In carrying out correct procedure and chemical calculations; the amounts of each substance will be found.

The heterogeneous starting mixture was first decanted and the less dense, non - polar immiscible hexane was carefully poured off the top of the mixture into a separate measuring cylinder. The quantity of hexane was then measured and it was found that there was a successive change in mass of hexane of 0.5ml; a difference of -3.85%. This loss of mass of hexane could be due to the process in which hexane was separated form the original mixture. This could be due to hexanes adhesion to glass. Once hexane was placed in separating funnel, it appeared that not all the hexane had been successfully decanted and that some was present of the glass walls of the beaker. In order to extract all hexane from the mixture, an addition of detergent to the separating funnel could have been implemented. However this would then increase the volume of the hexane as the detergent would mix with the hexane thus affecting the results and final measurements. Therefore there was a tendency for the final amount of hexane to be slightly less than that of the initial measurements. A method that could have been implement in order to attain more accurate results would be to add high pressure water to the inside of the separating funnel. The separating process of decanting then must be partaken in order to maintain highest possibility of gaining most accurate concentration of hexane from the mixture.

The remaining mixture then consists of both solid and liquid components. In order to separate the solids form the mixture the separation method of filtration was used in order to gain relatively accurate results. Once the sand and iron was filtered and left to dry, the iron was then able to be removed from the sand/iron mix. However, as the iron was left to dry, exposing it to the formation of hydrated oxide, rusting appeared throughout the solid mixture. Rusting is an electrochemical process which requires the presence of water, oxygen and an electrolyte (Roberge, 2006). In air, a relative humidity of over 50% provides the necessary amount of water. When a droplet of water containing a little dissolved oxygen falls on the iron in the mixture, the solid iron or Fe(s) under the droplet oxidizes (Roberge, 2006):

Fe(s) --> Fe2+(aq) + 2e-

The electrons are swiftly consumed by hydrogen ions from water (H2O) and dissolved oxygen or O2(aq) at the edge of the droplet to produce water:

4e- + 4H+(aq) + O2(aq) --> 2H2O(l)

Hydrogen ions are being consumed by the process. As the iron corrodes, the pH in the droplet rises. Hydroxide ions (OH-) appear in water as the hydrogen ion concentration falls. They react with the iron (II) ions to produce insoluble iron (II) hydroxides or rust (Roberge, 2006).

This then ultimately increased the amount of iron collected by 7.29% by magnetic separation. As the rust had formed on the iron, when weighed, the final measurement was 0.175g greater than the initial. It is evident that irons (Fe) atomic mass = 55.845. When Fe is exposed to the formation of hydrated oxide, the chemical formula becomes Fe2O3. Oxygen (O) atomic mass = 15.9994. Therefore to calculate the molecular weight of Fe2O3: 55.845*2+15.9994*3 = 159.6882 g/mol. As apposed to the molecular weight of Fe = 55.845g/mol. Therefore the molecular weight of iron when exposed to hydrated oxide becomes heavier than iron without the formation of rust.

Out of a total 5.5g of sand, 5.206g was extracted from the mixture. Although these results are relatively accurate, there was a percentage difference of -5.35%. This could be due to the fact that, as sand and iron were separated by magnetic separation, the sand had a tendency to get fixed between the iron and the external magnetic force. This typically reduced the accuracy and mass of sand weighed after the iron was extracted. Also, small amounts of oil that was present in the two solids may have caused the sand particles to fuse to the iron particles as they were magnetised.

In order to improve the accuracy of the iron and sand collected, the solids could have been exposed to a process called Nitrogen drying as apposed to leaving the iron fillings exposed to air for extended periods of time thus not allowing the formation of hydrated oxide to occur. Membrane Nitrogen contains only trace quantities of moisture which makes it very efficient in drying operations. Nitrogen provides an inert atmosphere for long-term preservation once the drying process is completed. This environment diminishes oxidation and no purge is required after drying is complete. Nitrogen also provides time saving since it can be used to rapidly pressurize a system (http://www.canadiannitrogen.com/def_drying.html).

The method of fractal distillation was used in order to separate the ethanol and the remaining homogeneous mixture. 22ml of ethanol was extracted form the mixture out of a total 25ml. This discrepancy in results could have been due ethanol's unique boiling point of 78.5 degrees; therefore causing small amounts of the ethanol to evaporate whilst the mixture was left for extended periods of time. It was evident that, whilst conducting the method of fractal distillation, the boiling point of ethanol was much higher than expected. The ethanol did not begin to evaporate until around 94.5 degrees. This could be due to the extensive addition of water to the homogeneous mixture. As ethanol and water have opportunity for hydrogen bonding, it appeared that due to the large quantity of water added to the mixture, it seemed to create extensive hydrogen bonds throughout the mixture. The more hydrogen bonding apparent within a solution, the stronger the inter-molecular forces become, therefore requiring more energy to break them apart. This means a higher temperature is required in order for the ethanol to be completely distilled. The discrepancy in the initial and final measurements of ethanol was a total of -12%.

This is due to the evaporation that occurred during the course of the experiment. Also methylated spirits is only 95% ethanol and 5% methanol. Methanol boiling point is 64.6 degrees and therefore, whilst collecting any impure substances, the methanol would have been boiled off once the temperature reached 64.5 degrees. This means that 5% of the solution would have been lost in this process therefore affecting the final results. To ensure that the results were as accurate as possible, the methanol must be collect once the temperature reached 64.5 degrees in a separate beaker and added to the ethanol that was boiled of at 94.5%. Also to ensure no evaporation occurs during the course of the experiment, it is imperative to completely cover the beaker that holds the mixture. This will improve any discrepancies in results.

Once the ethanol was distilled out of the mixture, all that was left was 1.3g of NaCl and 0.6g of Na2SO4. In order to calculate the amounts of each, precipitation reactions were required. In order to do this, Barium Nitrate Ba(NO3) was added to the mixture. Once the double displacement precipitation reaction were run to completion, the BaSO4 was then filtered out of the solution and weighed in order to complete calculations as to the initial masses of Na2SO4. Once the initial amounts of Na2SO4 were found, it was evident that only 94% of the initial amount was present. This was due to the fact that whilst filtering the BaSO4((s) some of solid leaked through the filter paper. Also, when pouring the solution through the filter paper, some of the BaSO4 remained on the sides of the glass beaker. This could be rectified by correctly folding the filter paper so that it had the greatest surface area and rinsing all of the BaSO4 through the filter paper with distilled water.

Sliver Nitrate, Ag(NO3), was then added to the remaining mixture in order to chemically react with the NaCl. Once the double displacement precipitation reaction was run to completion, the AgCl (s) was filtered out of the mixture. Once it was separated from the mixture, the filter paper was then weighed. By subtracting the original filter paper weight from the total weight, a mass of 1.636g was present of NaCl. This is 25.85% more than the initial measurement. The reason as to why there was an increase of 25.85% in mass of NaCl was because the filter paper had not been allowed to dry thus including the weight of the water in the final measurement of NaCl. To rectify this discrepancy in results, the filter paper must completely dry before being weighed. …
7.0) Conclusion

The aim of the extended experimental investigation was to validate the original masses of the different compounds presented in a mixture. These substances were unique in terms of their physical and chemical properties. Therefore, in order to separate the mixture into its original compounds, specific methods of separation were utilised to gain the most accurate results. Based on the background information and previous research, it was hypothesised that, in using these certain methods of separation, the original masses of each component would be authenticated.

The results showed that the the findings of this report generally supported the hypothesis in that fairly accurate final measurements generally matched initial measurements. The main discrepancies in results were the initial and final measurements of NaCl and Iron. These discrepancies were NaCl final measurement being 25.85% more than the initial measurement and the iron fillings final measurement being 7.29% more than the initial measurement. These results led to major findings such as the iron being exposed to hydrated oxide which produced rust which turned the Fe into Fe203. The Fe203 had a greater molecular weight than Fe which ultimately caused an inaccurate weighing of the Fe. Also NaCl finial measurement was greater than the initial because of the fact that it was weighed after only a short period of time after the reaction and therefore was not completely dry. This made the AgCl(s) heavier than it was, altering calculations and ultimately varying the final measurement.

Main recommendations included the use of Nitrogen drying when drying the iron fillings and sand. This stops rust forming and altering the results. Also in order to achieve most accurate results, the 5% of methyalted spirits, (methanol), that is boiled off at 64.5% must be collected and added to the ethanol once it is boiled off at 94.5%.

8.0) bibliography

* Deb Smith et al. (2006). Chemistry In Use, McGraw-Hill publications: NSW

* Rick Hoadly(2008).How do magnets work? (Online) Available from: http://www.coolmagnetman.com/maghow.htm (Accessed 2/3/2010) Referencing Internet Resources Using the Harvard System(online)

* Eddleman et al. (1987). Fractional Distillation Chemical Heritage Foundation, 315 Chestnut Street, Philadelphia, PA 19106 available from: http://www.chemheritage.org/EducationalServices/pharm/antibiot/activity/distil.htm (accessed 2/3/2010) Referencing Internet Resources Using the Harvard System(online)

* Mark Lefers (2004). http://www.biochem.northwestern.edu/holmgren/Glossary/Definitions/Def-N/nonpolar_covalent_bond.html (accessed 2/3/2010) Referenced using the Harvard System (online)

* Anne Helmenstine, Ph.D., (2009) Alkanes, Organic Chemistry Nomenclature & Numbering (online), 249 West 17th Street New York, NY10011, available from:http://www.about.com/gi/pages/mprivacy.htm (accessed 3/3/2010) Referencing Internet Resources Using the Harvard System.

* Professor Cram (2009). Chemical Bonds: Polar and Non-Polar Bonds(online) Available from: http://www.college-cram.com/study/chemistry/presentations/603 (accessed 2/3/2010) Referencing Internet Resources Using the Harvard System(online) * http://www.canadiannitrogen.com/def_drying.html

* Anthony Dunk, (2001) Methylater Spirits, available from: http://adunk.ozehosting.com/metho.html (accessed 2/3/2010) Referenced using the harvard system (online)

* Pierre R. Roberge, (2006) Corrosion Doctors. Rust Chemistry (online), Royal Military College of Canada, available from: http://corrosion-doctors.org/Experiments/rust-chemistry.htm (accessed 21/3/2010) Referencing Internet Resources Using the Harvard System.

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