Nickel is one of the five ferromagnetic elements. Because of the precise alloy used, the US "nickel" coin is not ferromagnetic, while the Canadian coin of the same name is up to and including the year 1958.The most common oxidation state of nickel is +2, though 0, +1 and +3 Ni complexes are observed.
The bulk of the nickel mined comes from two types of ore deposits. The first are laterites where the principal ore minerals are nickeliferous limonite: (Fe,Ni)O(OH) and garnierite (a hydrous nickel silicate): (Ni,Mg)3Si2O5(OH). The second are magmatic sulfide deposits where the principal ore mineral is pentlandite: (Ni,Fe)9S8.
Nickel can be recovered using extractive metallurgy. Oxy-hydroxide ores are treated using hydrometallurgy, and from sulfide mineral concentrates using pyrometallurgical or hydrometallurgical techniques. Sulfide mineral concentrates are produced by applying the froth flotation process.
Nickel is extracted from its ores by conventional roasting and reduction processes which yield a metal of >95% purity. Final purification to >99.99% purity is performed by reacting Nickel and carbon monoxide to form Nickel carbonyl. This gas is passed into a large chamber at a higher temperature in which tens of thousands of nickel spheres are maintained in constant motion. The Nickel carbonyl decomposes depositing pure nickel onto the nickel spheres. The resultant carbon monoxide is re-circulated through the process.
Naturally occurring nickel is composed of 5 stable isotopes; 58-Ni, 60-Ni, 61-Ni, 62-Ni and 64-Ni with 58-Ni being the most abundant (68.077% natural abundance). 18 radioisotopes have been characterized with the most stable being 59-Ni with a half-life of 76,000 years, 63-Ni with a half-life of 100.1 years, and 56-Ni with a half-life of 6.077 days. All of the remaining radioactive isotopes have half-lifes that are less than 60 hours and the majority of these have half lifes that are less than 30 seconds. This element also has 1 meta state.
Nickel-56 is produced in large quantities in type Ia supernovae and the shape of the light curve of these supernovae corresponds to the decay of nickel-56 to cobalt-56 and then to iron-56.
Nickel-59 is a long-lived cosmogenic radionuclide with a half-life of 76,000 years. 59Ni has found many applications in isotope geology. 59Ni has been used to date the terrestrial age of meteorites and to determine abundances of extraterrestrial dust in ice and sediment. Nickel-60 is the daughter product of the extinct radionuclide 60Fe (half-life = 1.5 Myr). Because the extinct radionuclide 60Fe had such a long half-life, its persistence in solar_system materials at high enough concentrations may have generated observable variations in the isotopic composition of 60Ni. Therefore, the abundance of 60Ni present in extraterrestrial material may provide insight into the origin of the solar system and its early history.
The isotopes of nickel range in atomic weight from 52 amu (52-Ni) to 74 amu (74-Ni). However, there is also Nickel-78, whose half-life was recently measured to be 110 milliseconds, which is believed to be an important isotope involved in supernova nucleosynthesis of elements heavier than iron.
Apparatus and Materials:
-
Nickel ammonium sulphate, NiSO4(NH2)SO4 ∙ H2O
- Concentrated HCl
- Dimethylglyoxime reagent
- Distilled water
- Dilute ammonia solution
-
Beaker (cm3)
- Bucher funnel
- Dropper
-
Thermometer °C
- Analytical Balance
Procedures:
-
One 0.3-0.4 g sample of Nickel ammonium sulphate, NiSO4(NH4)2SO4.6H2O was weighed out accurately into 250 cm3 beaker. The salt was dissolved in distilled water, 2-3 cm3 concentrated HCl was added and diluted it to approximately 150 cm3.
-
The salt was heated to 70-80 °C, a slight excess of dimethylglyoxime reagent was added and then concentrated ammonia solution was added drop wisely and with constant stirring until precipitation occurs and then in slight excess to complete precipitation.
- The precipitation was digested for 20-30 minutes on the steam bath and the solution with dimethylglyoxime reagent for complete precipitation.
-
The precipitation was allowed to stand for one hour to cool. The cold solution was then filtered through using suction apparatus and wash well, previously dried to constant weight by heating to 100-120 °C and weighing after cooling in a desiccator’s.
- The precipitate was dried it at 110-120 for 45-60 minutes. After that it was allowed to cool in a desiccator’s and weighed it.
-
The drying was repeated until constant weight is attained. Weigh as Ni(C4H7O2N2)2 which contains 20.32 per cent Nickel.
Data and Result:
Calculation and Analysis:
RAM of Ni
Theoretically, % of Ni = ----------------------------------------- X 100 %
RMM of NiSO4(NH4)2SO4.6H2O
58.69
= -------------------------------------------------------------------------------------------- X 100 % 58.69 + 32.07 + 4(16.00) + 2[14.01 + 4(1)] + 32.07 + 4(16.00) + 6[2(1) + 16.00]
58.69
= -------------- X 100 %
394.85
= 14.86 %
Practically, % of Ni in Ni(C4H7O2N2) = 20.32 %
∴Amount of Ni in complex = % of Ni(C4H7O2N2) X Weight in Nickel complex
= 0.2032 X 0.20 g
= 0.04064
Amount of Ni complex
% of Ni in Nickel salt = ----------------------------------------------- X 100 %
The weight of NiSO4(NH4)2SO4.6H2O
0.04064
= ------------- X 100 %
0.31 g
= 13.11%
Compare practical percentage with theoretical percentage,
Different in percentage = Theoretical – Practical
= 14.86 % – 13.11 %
= 1.75 %
Discussion:
From the calculation stated above, we get the theoretical percentage of nickel is 14.86 % in nickel ammonium sulphate salt (NiSO4(NH4)2SO4.6H2O). Practically, the percentage for nickel we get is only 13.11 %. Obviously there is 1.75 % different from theoretical value. Since result from experiment wouldn’t be exact as theory, but there is still have difference that we have discuss and stated below why there is such changes or gaps.
In the beginning of the experiment, the given salt, nickel ammonium sulphatesalt (NiSO4(NH4)2SO4.6H2O) is weight accurately using two-decimal balance because the range of mass is in between 0.3 to 0.4g. When the weighing of nickel ammonium sulphate salt is carry out, fan is make sure to be switched off and decrease or downgrade any air movement in the lab so that the air movements won’t be able to affect the reading of the balance. The above step also to prevent more dust or other particles that is small and wondering around the room in the air attached to the plate of the balance and increase the reading of actual mass value causing error in result. The mass we get is 0.31g. Since the mass is in the range requested, error in calculation related this mass will be secure.
After weighing, distilled water is added with the nickel salt in a clean 250cm3 beaker to dissolve the salt. After the nickel salt is completely dissolve in visible vision, hydrochloric acid is added into the beaker and distilled water is added further to make the solution reach approximately 150cm3. Hydrochloric acid added is act as a catalyst where incite the solubility of nickel salt in water. The 150cm3 solution is then heated to 70-80oC to increase the solubility. Dimethylglyoxine reagent, CH3-C(:NOH)-C(:NOH)-CH3, as a precipitate reagent added to the heated solution to provide precipitation happening. As a positive reaction, a red precipitate, Ni(C4H7O2N2)2, will clearly see forming in a large quantity in the test solution. It is suggested that slight excess of the reagent added but not larger excess because larger excess of the reagent may increase the solubility or contamination of the precipitate. After adding the dimethylglyoxine reagent, concentrated ammonium is added immediately into the test solution and constant stirring is given. Concentrated ammonium needs to be added until full or complete precipitation reach. The complete precipitation here is important to be confirmed fully formed. Incomplete precipitation in this part will cause the mass value get for the nickel complex in further procedure below appear to be false and incorrect. It is suggested that added slightly excess of concentrated ammonium into the test solution to make sure precipitation is complete. The chemical process of the precipitation is shown as equation below:
Before filter off the precipitate for recording its weigh, it is allowed to digest in the test solution for a period of time in high temperature. The test solution will allow to heat up in water bath where the temperature is about the boiling point of the solution. The digestion is to further ensure that precipitation is completed and increase the size of the particles of the precipitate making easy the precipitate to filter out. The process is using about half an hour to confirm the precipitates have digested and dimethylglyoxine reagent used slightly to test the completion of precipitation. No more red precipitate form mean the reaction is complete. When digestion in water bath, glass rod is removed from the test solution and stirring is stop. Also when digestion is carrying out, the beaker is suggested to cover with glass to keep away any particles in the air from affecting the process, yet result too. The precipitation steps stated above do cause a lot of error in result of other groups, this may due of lack of time accessing the experiment and uncompleted precipitation have use to continue for digestion.
The precipitate is then allowed to cool down in fridge for about 30 minutes to let the filtration easier to carry out. Filter paper is weigh for its mass using two-decimal balance because we have to reduce the weigh of filter paper to get the weigh of the precipitate where is after the filtering and after heating. Caution is taken when taking the filter paper weigh. The size of filter paper must be suitable to be fitted into the crucibles. Filter paper must at least cover up over the minimum level of crucibles. When accessing to the filter apparatus where we are using the Hirsh flask, make sure the pump is on and the airway is clear opened to make the suction of water available when pouring the test solution on the crucibles. When pouring the test onto the crucibles, it is suggest that pour slowly in small amount first and wait the water finish pass through the filter paper then only continue for further pouring. This is to avoid excess of test solution that included small amount of precipitates spill out from filter paper. Use chilled distilled water to wash the precipitate. After completion of filtration, close the airways to stop the suction from the pump. This will avoid the filter paper from tearing apart when we want to take it out from crucibles. If the suction is still available, filter paper will stick on the crucible and may cause tear off when we directly take it out.
Because of any reagent that may have been carried down by the precipitate is volatilised, the precipitate filtered out is then dried at 100-120 oC. To work in high accuracy where large precipitate is available, 150 oC of temperature is suitable for drying. After the drying for about 1 hour, the precipitate is taken out and put in the desiccators to double confirm the precipitate is completely dried up before weighing. Some of the group whom doesn’t put their precipitate in the desiccators will comes out with the over value of the mass when weighing. This shows that absorption of water after heating is important to make the result accurate. After that, wash the precipitate with cold distilled water to completely wash away chlorine that is in the precipitate. Skipping the washing will have mass value of nickel complex to be higher than aspect. The precipitate is then weighed using two-decimal balance, and again caution is making when weighing. After weighing, the precipitate is dried again at 110-120 oC for second heating with duration about 60 minutes. Same as the first drying, after heating, the precipitate must put in the desiccators first before weighing. The process of re-heating, re-washing and re-weighing is repeated until there is a constant of mass value. As compare with first heating, the weigh of precipitate of second heating should be lower than it, if not there are error or improper handle during the experiment work out.
In the calculation part, practically we use the precipitate which also known as nickel complex, Ni(C4H7O2N2), where we have know contain 20.32 % of nickel. We use it to multiply with the weight of nickel complex after final heating and get the value for amount of nickel in nickel complex. This value will then divide with the weight of nickel ammonium sulphate that we get from beginning of experiment and multiply by 100 to get the percentage of nickel in nickel ammonium sulphate. The practical value we get is 13.11 %, which is 1.75 % differing from theoretical value. This may due to the incomplete precipitation because we are insufficient time to access the complete experiment. The precipitate solution is been cold down when it still haven’t finish its precipitation process. And also the wash off of chlorine may not completely that cause our practical percentage differs from theoretical percentage.
Precaution steps:
- Fan is confirmed switched off to prevent any air movement that will giving error or false mass value to the reading.
- Acidic and basic solution ued in the experiment are highly in their own strength, each of them may cause corrosive to our skin or other physical contact, it is advise to be more careful when handle both of these material. Gloves are protective from the corrosion, wear it when access the materials.
- Concentrated ammonium will release a strong smell that will irritate our nose. Mouthpiece is advised to wear to avoid any dizziness or other defect of the smell.
- Glass rod is not allowed to leave in the beaker while digestion precipitate in water bath. Leave the glass rod out from the solution and clean it.
Conclusion:
- The percentage of nickel from theoretical calculation is 14.86 % respectively.
-
The percentage of nickel get in the NiSO4(NH4)2SO4.6H2O is 13.11 %.
- Compare with theoretical percentage of nickel in salt which is 14.86 %, it is 1.75% different from the practical percentage.
References:
- http://www.newi.ac.uk/buckleyc/gravi.htm
- http://wulfenite.fandm.edu/labtech/gravanal.htm
- http://www.chem.tamu.edu/class/majors/tutorialnotefiles/gravimetric.htm
- http://www.dartmouth.edu/~chemlab/chem3-5/qual_cat/overview/procedure.html
- http://www.dartmouth.edu/~chemlab/chem3-5/qual_cat/full_text/procedure.html
- Pre-U chemistry, Longman Pearson. 2004
- Chemistry fourth Edition, Silberberg
