A controlled variable is a variable that stays the same throughout an experiment such as: adding a specific sum of H2O to prove tubings filled with different sums of ammonium chloride. An independent variable is the variable that is changed during an experiment, e.g. different sums of ammonium chloride added to divide trial tubing in an experiment. A dependent variable is a variable that alterations because of the independent variable, e.g. the difference of temperatures when the first crystals begin organizing in the separate trial tubings filled with different sums of ammonium chloride.
In this experiment the controlled variable will be 10mL of H2O that is added to each trial tubing filled with ammonium chloride. The independent variable will be the different sums of ammonium chloride put into each trial tubing. The dependent variable will be the temperature of the first crystals looking in the trial tubing filled with different sums of ammonium chloride that are dissolved in H2O.
Ammonium Chloride
Ammonium chloride is a substance which has the molecular expression NHa‚„Cl and is extremely soluble in H2O. It was foremost manufactured during the thirteenth century in Egypt and Europe and was originally known as sal ammoniac. It is used for a assortment of intents. In medical specialty it is used as an expectorator, which clears the emotionlessness from the bronchial tube, lungs and trachea country. It is besides used as a constituent in dry cell batteries, an ingredient in cough medical specialty and as a dietetic addendum to keep pH degrees.
Solubility
Solubility is when a substance is dissolved in a dissolver such as H2O. This is so measured in g/100mL to cipher the solubility of that substance in the dissolver, e.g. The solubility of 50g of Ammonium chloride would be shown as 50g/100mL of H2O. Solubility is a method used to cipher how much of a substance can be dissolved in a dissolver. This method can be explained in three different ways: a concentrated solution, an unsaturated solution and a supersaturated solution.
A concentrated solution is where no more solute can fade out in the dissolver at a specific temperature.[ 1 ]An unsaturated solution is where more solute can be added to fade out in the dissolver at a specific temperature.However, a supersaturated solution is where an unexpected sum of solute can still be dissolved in a dissolver at a specific temperature. A supersaturated solution can merely be achieved ( with trouble ) by altering the conditions of the concentrated solution.
In this experiment, the substance is Ammonium chloride and the dissolver is H2O and when assorted together, the Ammonium chloride dissolves. Repeating this with different sums of ammonium chloride gives us the solubility of Ammonium chloride in g/100mL of H2O. When adding more ammonium chloride, the soap sum of the substance that can fade out in the dissolver is discovered, this is called a concentrated solution. If a specific sum of ammonium chloride that ever dissolves in g/100mL of H2O is used, it is called an unsaturated solution because more of the substance can be added to the dissolver, to fade out. If the concentrated solution of the substance is reached but more of the substance is added and surprisingly dissolves in the dissolver, it is called a supersaturated solution. This experiment can dwell of a saturated or an unsaturated solution because the solubility of Ammonium chloride in H2O is unknown.
Solubility Curve
Solubility curve is a graph of solubility V temperature. Solubility curves are used to foretell the maximal sum of a substance that can be dissolved in a dissolver at a specific temperature.
Solvents
A dissolver is a substance that is either a liquid, solid or gas that dissolves a solute to make a solution. The maximal sum of a substance that any dissolver can fade out depends on the temperature of the dissolver, e.g. If H2O can fade out a upper limit of 30g of ammonium chloride at 50A°C, but the temperature was increased to 60A°C it could fade out more of the ammonium chloride. There are two classs of dissolvers: polar and non-polar dissolvers. A polar molecule has two sides ; one is positive and the other negative, besides known as a dipolar molecule. Polar molecules have polar bonds, though some can hold polar bonds but are non-polar molecules. This is because the polar bonds are arranged in a manner that they cancel each other out. The overall mutual opposition of a molecule depends on the way of the bond dipoles in a molecule which is determined by the form of the molecule.
Polar dissolvers can hold a little electrical charge because of the form of the compound. A compound such as H2O has the H atoms at opposite angles of the O atom. The H atoms can make a little electrical charge because of the way of the bond dipoles, which is determined by the form of the H atom. A molecule may blend in a polar dissolver if it has a mutual opposition of its ain. Salt and saccharify both dissolve in H2O easy because their molecules are attracted to the little electrical charges of H2O. Non-polar dissolvers do n’t hold an electrical charge and can non blend with a polar dissolver.
Polar and non-polar dissolvers use a dielectric invariable to supply a unsmooth step of the dissolvers mutual opposition. Dielectric invariables are the electrical belongingss of a dissolver utilizing a capacitance, in which electrical currents pass through. Non-polar dissolvers are considered to hold a dielectric invariable of less than 15. The mutual opposition index measures the ability of a dissolver to fade out different polar stuffs. The consequences of both these trials are used in a tabular array of common dissolvers and in future can be used for placing dissolvers in chemical procedures.
Polar and non – polar dissolvers are related to this experiment because H2O is a polar dissolver and ammonium chloride is a polar solute. This means that the two can blend together. If either one was a non-polar dissolver or solute, they would n’t blend because they do n’t hold a positive or negative pole that binds them together.
Endothermic Chemical reactions
An endothermal reaction is where a merchandise absorbs energy from its milieus, doing its milieus to drop in temperature. In an exothermal chemical reaction the reactants have more energy than the merchandises. However, in an endothermal chemical reaction the merchandises have more energy than the reactants because it absorbs the energy from the reactants and the environment.
If ammonium chloride is added in a beaker filled with H2O and dissolved, the beaker would go cold. This is because it is an endothermal reaction, where the ammonium chloride absorbs the energy from the dissolver ( H2O ) and its milieus. This is why we heat ammonium chloride, so that more of it can be dissolved in a dissolver ( H2O ) and the temperature will non drop quickly.
What is being investigated?
The thought of this probe is to detect what happens when ammonium chloride is added in a trial tubing filled with a specific sum of H2O and heated. The following portion of the probe is to detect what happens when the merchandise is allowed to chill.
How is it being investigated?
This experiment is being investigated by utilizing a scope of equipment. An electronic balance is being used to weigh the ammonium chloride and acquire an accurate consequence, and a burette to mensurate an accurate, 10mL of H2O which is added into a trial tubing with the ammonium chloride. An electric hot home base is so used to heat up this mixture, and fade out it while in the procedure of heating. Next, a rejoinder base is used to chill down the mixture, so that you do n’t hold to keep the trial tubing with your manus since it would be truly, truly hot! Finally, a digital thermometer is used to acquire a consequence of the temperature of when something happens in the trial tubing, when it is chilling down. These consequences of the experiment are written down and set into tabular arraies and graphs so that others may understand how the consequences were gathered utilizing these equipment.
How will the consequences be analysed?
The consequences will be analysed by happening tendencies in the statistics that have been written down. These consequences will so be put into a tabular array and graph. The tabular array will be analysed to look into if there are any consequences that do n’t suit in and if there is a ground why this consequence occurred during the experiment. The graph will be analysed by happening if there is a tendency between the consequences on the graph ( e.g. a changeless ) and how they match up. Next, the graph is analysed by look intoing if there is any incompatibilities or consequences that seem out of topographic point. Finally, the graph is analysed by proving or look intoing the consequences to see if they are right or wrong.
Materials
- solid ammonium chloride
- 2 rejoinder bases
- 500 milliliter beaker
- Hand lens
- 250 milliliter distilled H2O
- burette
- burette holder
- big clean trial tubing
- electric hot home base
- spatula
- stirring rod
- digital thermometer
- 2 rejoinder base clinchs
- heat mat
- electronic balance
- black card
- safety spectacless
Method
- 4gms of solid ammonium chloride was measured and the existent mass was recorded.
- The solid ammonium chloride was put into the big clean trial tubing.
- The burette was filled with distilled H2O till the degree reached 10mL.
- This 10mL of H2O was added to the big clean trial tubing with the solid ammonium chloride.
- 300mL of hot H2O was added to the 500mL beaker.
- The beaker was placed on the electric hot home base.
- The beaker was heated up to boiling temperature and the big trial tubing was easy placed inside with the H2O degree in the beaker 3cm higher than the H2O degree inside the trial tubing utilizing the rejoinder base and clinch.
- The mixture in the trial tubing was gently stirred utilizing the glass stirring rod until dissolved.
- The big trial tubing was removed from the beaker after the solid ammonium chloride dissolved and allowed to chill.
- The big trial tubing was stirred and watched utilizing the manus lens and the black card to detect the first crystals signifier.
- The digital thermometer was used to mensurate the temperature of the first crystals organizing.
- The mixture was so heated up once more and utilizing stairss 7 -11 the procedure was repeated two more times to acquire the most accurate consequences of the crystals organizing with 4gms of solid Ammonium Chloride.
- Stairss 1 – 13 was repeated once more utilizing 5g, 6g and 7g of solid ammonium chloride.
Consequences
Temperature of first crystals looking
Ammonium Chloride ( gms )
- Trial 1 ( A°C )
- Trial 2 ( A°C )
- Trial 3 ( A°C )
Average
- 3.99
- 73.4
- 73.6
- 73.3
- 73.43
- 5.02
- 80.5
- 83.6
- 75.8
- 79.96
- 6.02
- 85.5
- 87.5
- 89.5
- 87.50
- 7.04
- 94.4
- 94.1
- 95.2
- 94.56
To happen the mean temperature of each of the four trials of ammonium chloride, the recorded temperature of the three tests were added together and so divided by three. E.g.
Solubility of Ammonium Chloride
Mass of Ammonium Chloride ( g )
- Volume of Water ( milliliter )
- Solubility ( g/100mL )
- Temperature ( A°C )
- 3.99
- 10
- 39.9/100mL
- 73.43
- 5.02
- 10
- 50.2/100mL
- 79.96
- 6.02
- 10
- 60.2/100mL
- 87.50
- 7.04
- 10
- 70.4/100mL
- 94.56
To happen the solubility of ammonium chloride in g/100mL, we multiplied the mass of ammonium chloride and volume of H2O by 10. E.g.
Harmonizing to the graph at a temperature of 55A°C, 25g/100mL of ammonium chloride will fade out in H2O. This is linked to the trend-line that has been added into the graph to demo the solubility of ammonium chloride at 0A°C and at 100A°C.
Accepted Valuess
Discussion
Tendencies
The consequences in Table 1, 2 and Graph 1 all have one tendency in common ; as the temperature increases, the solubility of ammonium chloride increases. This tendency shows that the consequences are dependable but non valid because graph 2, which is the recognized consequences, shows that the solubility curve of the two graphs do non fit i.e. the values do non fit but they follow the same form. Another tendency in the consequences is the temperature, which shows that for the solubility of ammonium chloride, each gm that was tested approximately differs by 7A°C. This tendency is neither dependable nor valid because they do non fit graph 2 and the forms in the graph are different.
Saturated, Unsaturated or Supersaturated
These consequences besides indicate that this could be a concentrated solution, unsaturated or a supersaturated solution because 4g of ammonium chloride dissolved in H2O at a temperature of 73.43A°C, though the 7g of ammonium chloride dissolved at a higher temperature of 94.56A°C significance that it took longer to fade out 7g than 4g. This, in bend, shows that if more ammonium chloride was added to the 7g of ammonium chloride it would hold taken longer to fade out and once it passed boiling temperature H2O would hold evaporated till there was no dissolver left and there would still be ammonium chloride. This would intend that 4, 5, 6 and 7g of ammonium chloride was an unsaturated solution. This is an mistake because it is wholly different when compared to the consequence of graph 2. This mistake means that something occurred during the experiment which made the ammonium chloride at a higher temperature or merely a random mistake where the H2O was heated before the ammonium chloride was put into the beaker. This mistake has significantly changed the consequence as it has increased the temperature of disintegration when it should be a batch lower.
Comparison ( cogency and dependability )
Table 1 shows the 4, 5, 6 and 7 gms of ammonium chloride was tested three times to acquire the most accurate consequence. These three consequences were so divided to give an norm. The norm of the 6 and 7 gms of ammonium chloride in comparing to chart 2 is dependable because the solubility of ammonium chloride increases with the temperature. The norm of the 4 and 5 gms of ammonium chloride in comparing to chart 2 could be dependable but the per centum of mistake is excessively high for this to be acceptable significance that there was an mistake in the consistence of the experiment.
‘Solubility of Ammonium Chloride ‘ shows the four norms of each trial of ammonium chloride, with a trend-line that predicts the solubility of ammonium chloride between 0A°C and 100A°C. In add-on the graph shows that when you keep adding more and more ammonium chloride the temperature for it to fade out will increase, but merely by a few grades each clip. Graph 2: ‘Accepted Values – Solubility of Ammonium Chloride ‘ are the recognized values of the solubility of ammonium chloride. In comparing to chart 1, both graphs have a curve, though graph 1 has more curve than graph 2, where the curve is really little. Graph 1 and 2 do non fit at all, intending that there are mistakes and/or inconsistences in this experiment.
Table 1, 2 and Graph ‘Solubility of Ammonium Chloride ‘ all fit the theory that ammonium chloride dissolves in H2O. When we match up all the consequences in this experiment, they clearly do non fit the recognized values. The recognized values are immensely different as graph 1 shows that 39.99 gms of ammonium chloride dissolves at 73.43A°C and graph 2 shows that 39.99 gms of ammonium chloride dissolves at approximately 28.12A°C. The consequences fit the theory because all four trials of ammonium chloride dissolved in H2O. The lone factors that could hold changed this result could hold been the sum of substance in a dissolver which is heated to a specific temperature. In the terminal graph 1 explains as the temperature increases, so will the sum of ammonium chloride that dissolves.
Mistakes
Possible mistakes that could hold occurred during the experiment are: the solid did n’t fade out decently, temperature could hold been incorrect during the chilling down procedure, the recrystallization of the ammonium chloride in H2O was hard to judge and malfunction of equipment could hold caused mistakes. The ground why the solid might non hold dissolved is because the temperature might non hold been high plenty or I did n’t stir it plenty. In the instance of a random mistake the solid might non hold dissolved but the oculus might non hold been able to see a really little atom even with a little magnifying glass. The ground the temperature could hold been incorrect is because when I stirred the mixture, the heat from the underside of the trial tubing would hold mixed with the cool temperature at the top of the trial tubing, intending that when you saw the first crystals looking the temperature could hold still been altering. During the experiment the ammonium chloride solution from the first tests was recycled to be used for farther tests. This could hold changed the pureness of the ammonium chloride because it looked really different to the normal ammonium chloride. This could intend that while the weight did non show a job, it may hold non been wholly dry which could impact the consequences. The malfunction of equipment could hold occurred without my cognition, such as the balance graduated table being inaccurate ( e.g. the little empty cupcake cups on the graduated table did non equilibrate at 0 ) . Another malfunction could hold occurred with the thermometer non working decently.
The loss of ammonium chloride non fade outing could hold lowered the solubility of the substance. The likeliness of the graduated table non working is really low and could be counted as a random mistake, but if it was n’t working the solubility of the substance would be lower than expected if there was less ammonium chloride and higher if there was more ammonium chloride. The recrystallization could hold been the exact same as normal solid ammonium chloride or it could hold weighted more or less. This would do the reply higher if the ammonium chloride weighed more than it should. Overall I believe the consequences and replies I recorded might hold been a spot excessively high or even low, but I decidedly know that they are n’t exact. One manner to perchance better the experiment is to utilize the exact sum of H2O and ammonium chloride to acquire a measuring of solubility ( g/100mL ) . This would turn out to be more accurate and would be better suited in a beaker, on top of the electric hot home base as the heat would be dispersed around the full beaker. Further probes that could be included into this experiment could be happening out the concentrated solution of ammonium chloride at a specific temperature. This would be good because it is really likely that every group would acquire different consequences and have to explicate more in their treatment about mistakes and if they think that their reply is valid or non.
Improvements
One manner to perchance better the experiment is to utilize the exact sum of H2O to acquire a measuring of solubility ( 100mL ) . This would turn out to be more accurate and would be better suited in a beaker placed on an electric hot home base as the heat would be dispersed around the full beaker. Further probes that could be included could be happening out the concentrated solution of ammonium chloride at a specific temperature. This would be good because it is really likely that every group would acquire different consequences and have to explicate more in their treatment about mistakes and if they think that their reply is accurate or non.
Decision
In decision I discovered that 4, 5, 6 and 7 gms of solid ammonium chloride was soluble in H2O at different temperatures. The hypothesis that different sums of ammonium chloride will fade out in H2O at changing temperatures was answered. The consequences that I recorded were n’t valid because they did non fit the recognized values, though the consequences were dependable in some instances as they did hold a form and this form matched the recognized values.
References
- //www.wisegeek.com/what-is-ammonium-chloride.htm. Last Updated March 13th 2013.
- Survey on Chemistry 1, page 295-96.
- //www.wisegeek.com/what-is-a-polar-solvent.htm: Last Updated: 14th March 2013.
- //www.erowid.org/archive/rhodium/pdf/solvent.miscibility.pdf: Last Updated 14th March 2013.
- http: //www.bbc.co.uk/schools/gcsebitesize/science/add_aqa_pre_2011/chemreac/energychangesrev1.shtml: Last Updated 14th March 2013.
- hypertext transfer protocol: //en.wikipedia.org/wiki/Solubility_table: Last Updated 13th March 2013
