Observation :

Table 1: Calculated values associated with the reaction between Silver nitrate and copper

Trial #	Mass of Dry Silver      Residue (g)	Theoretical Yield (g)	Percentage Yield (%)
1	1.837 g	0.664 g	277 %
2	1.28 g	0.71 g	180 %
3	1.166 g	0.67 g	174%
4	0.749 g	0.73 g	102 %
5	0.72 g	0.73g	98 %

                  When the amount of actual yield ( mass of dry silver residue ) becomes far high compared to the theoretical yield, the resulting percent yield greater than 100% which is not correct.     

Figure 1: Copper wire and the dried silver residue of Group 5 A.M 

- the color of the copper wire quite faded away and turns into quite reddish from the original color which is quite brownish orange. 

Figure 2: Silver metal forming from the reaction of Silver nitrate and copper wire.

Evaluate:

f.) In order to improve the conducted experiment that would result in an increased yield, the silver residue had to be made sure that it was dried completely. Also, the amount of silver residue must be maintained as much amount as possible during the decantation process because if  there's too much silver residue lost, then the percent yield will decrease.


g.) i. If the silver residue will not be completely dried, the mass of the water would be added to the mass of the silver, thus would affect the actual yield of the product. The percent yield would be higher than hundred percent because the actual yield would be higher than the theoretical yield.

ii.) The percent yield of the reaction wouldn't be affected even though the silver nitrate used was old and had deteriorated over time due to some conditions such as exposure to ultraviolet lights, and decreased its mass as a result. As long as mass of the silver nitrate used was not changed before the reaction (or during), it wouldn't affect the percent yield.  

iii.) If the water used was tap water instead of distilled, the percent yield would be affected because some of the chloride ions in the tap water will react  to silver thus making the mass of the silver to decrease because of double displacement reaction compared to a single displacement reaction ( with distilled water ) where the silver was left not reacted to any other substances.

Sources of Error in the Experiment: 
                     * If the mass of the silver residue was measured while it's not dried completely, it will cause a huge amount of actual yield because some of the mass of the water left in the residue will add up in the mass of the silver.
                     * The weighing scale is not calibrated correctly or talking and moving a lot while measuring the mass of a substance or object that may affect the resulting mass given by the scale. This is because the weighing scale used to measure things in the experiment is so sensitive and can be affected by just vibrations in the air.
                    * Many silver residue were lost during the decantation process, that might result to very low percentage yield.
                    * The data collected were not rounded off correctly or rounded to insignificant digit(in this case, it has to be rounded to the nearest 0.01 digit)
                    * The percent yield will be far less if the water used is tap water instead of distilled water because the chloride ions in the tap water will react with silver using up some of it, resulting to decrease in mass.
                 

Design

This lab was performed to purify silver from silver nitrate by using copper wire. Before we performed the lab we must make sure that we had all the equipments, materials and using the safety clothing. The lab was performed by adding a copper wire into a solution of silver nitrate. The result of the experiment wass silver metal and copper nitrate. Silver nitrate had 0.00615165 mol AgNO3, while copper had 1.123982 mol AgNO3.

Synthesis (i)
Place the silver in a porcelain crucible, then covered and heated with acetylene torch until the crubicle turned a bright orange glow. The molten silver will leave hot beads of freshly-solidified silver, then allowed to cool and then collected. Place the cooled silver in 50 mL beaker labeled solution A. Then filled about 3/4 full with concentreted nitric acid.Covered it with 1000 mL beaker and heated on sand bath. The expected outcome will be a reddish-brown fumes indicates as nitrogen oxides, and remained inside the 1000 mL beaker until the ventalation system carried out the fumes. The solution become yellow and then green. NExt, place the remainder silver in another beaker and covered withe HNO3. Add HCl to this beaker, with ratio 3HCl : 1HNO3. Because of the acid reacts with silver, silver chloride will precipated out as white clumps. The precipate will increase steadily for 4 hours with the final colour green. Labeled this beaker as solution B. After that, dilute the solution A 3 times its volume with distilled water. Reddish-brown nitrogen oxides will be released during dilution, then the green color of the liquid will turn to pale blue. Use a Buchner funnel and vacuum filtration flask to filter the solution. Place the filtrate on a hot plate to be evaporated, to carry off the nitric acid vapours. When the first silver nitrate cystals begin to form, discontinued the heating. Repeat the process to get purer silver nitrate. And for solution B, dilute the solution B 3 times its volume with distilled water as well, to cause the silver chloride to re-precipate. Use a Buchner funnel and vacuum filtration flask to filter the solution, and then wash it. Place the filtration in a clean beaker and covered with 25 mL of distilled water. Add three or four crystals sodium thiosulfate to the water and stir with a glass rod, to solubilize the silver chloride. Use a cleaned copper wire as the preliminary attempt at plating out the silver. After 10 minutes the wire in the solution, the wire began to assume a silvery coating, but the solution has to be remained clear. With wooden tongue depressor, silver metal will be scrapped off. This metal mostly black and crumblly, was saved for making silver nitrate solution of higher purity.

Safety precautions
-The safety goggles were worn at all times, because acids might cause lost of sight instantly.
-The acids were not heated without adequate ventilation. The vapors were collected by a fume hood which carries tthem out
-The fume cupboard was tested with a steam of smoke to make sure vapours were already being removed.  Ammonium chloride "smoke" could also be used which was produced from the vapours of hydrochloric acid and ammonia for testing the fume cupboard.
-Nitrogen dioxide shouldn't be inhaled under any circumstances because it is very poisonous.
- Do not pour silver, copper, or nickel solution down the sink, put in the recycle garbage bin
-The silver and its compounds were kept away from oxalic acid, oxalates, acetylene, calcium carbide, strong reducing agents or prolonged exposure to ammonia.

http://www.crscientific.com/article-silver.html

Analysis - Testable Question's answer

In a reaction of copper wire and silver nitrate the limiting reactant is silver nitrate because when it's calculated the number of moles in silver nitrate is less than the number of moles in copper wire.

Graph: graph between theoretical yield against silver nitrate, silver nitrate is in the x-axis and theoretical yield in the y-axis, since silver nitrate is independent variable so it is in the x-axis. And theoretical yield is dependent variable, so it is in the y-axis

Analysis - Graph of percentage yield against the mass of silver nitrate used

Figure 1: Graph correspond to analysis d.

Mass of silver nitrate (g AgNO3)	Percentage yield (%)
1.037	81
1.006	107
1.185	88
1.272	85
1.045	279
1.15	99
1.211	296
1.12	180
1.05	174
1.15	103
1.27	419
1.34	156
1.4	181

Table 1: table correspond to figure 1

Synthesis
(h)Ion-exchange resin can be used to remove poisonous ions from solution, replacing them with harmless ions, such as sodium and potassium. This method will be effective, because ion exchange materials contain loosely held ions which are able to be exchanged with other ions in solution that contact with ion exchange resin. Ion exchangers are containing insoluble acids or bases and salts, and this enable them to exchange either positively charged ions or negatively charged ions. And the other advantages of this method are the ion exchange process required very low costs & very little energy, and well maintened resin can last for many years. Therefore, ion-exchange resin method will be effective
http://www.dowwaterandprocess.com/products/periodic_table/pt_cu.htm
http://nzic.org.nz/ChemProcesses/water/13D.pdf

Equipment and materials:
-Safety goggles
-Lab apron
-Latex gloves
-Paper Towel (tissue paper)
-Masking tape
-wooden splint ( or popsicle stick )
-stirring rod
-wash bottle of distilled water
-aluminum foil
-100 mL beaker (35.2 g)
-two 250 mL beakers(99.96 and 116.67 g)
-12 inches copper wire (0.762 g)
-silver nitrate crystals, AgNO3 (S) (1.05g)
-a pair of scissor

Hypothesis: If copper wire react with silver nitrate, the expected outcome will be silver and copper(II) nitrate, since single displacement reaction will be occurred due to copper is above silver on the activity series. Then according to table of solubility of ionic compound, copper(II) nitrate will have high solubility. Therefore copper nitrate would tent to remain in solution

Testable question :  In a reaction of copper wire with silver nitrate in solution, which reactant is the limiting reagent?

Pictures from the lab

 Image 1. The resulting silver that has been removed from the liquid

Image 2. The removed silver that has been dried for one day

Purpose: to determine at what concentrations of silver nitrate and copper wire could be formed  from solution.

Analysis - Limiting Reagent, Theoretical Yield and Percentage Yield

Based on our observation, these are the amount of:

Silver nitrate: 1.045 g

Copper: 0.762 g

Resulting Copper nitrate: 065 g

Resulting Silver: 1.837 g

To find the limiting reagent we have to balance the equation first:

2 AgNO₃ + Cu --> Cu(NO₃)₂ + 2 Ag

Now we have to find the mol of each resulting elements:

nAgNO₃ = 1.045 g AgNO₃ x 1 mol AgNO₃/(107.8682 + 14.0067 + 2(15.9994)) g AgNO₃ = 0.00615165 mol AgNO₃

nCu = 0.762 g Cu x 1 mol Cu/63.546 g Cu = 0.011991 mol Cu

For the last step, we need to make the mol equal:

nCu = 0.011991 mol Cu x 2 mol AgNO₃/1 mol Cu = 0.023982 mol AgNO₃

:: From the calculation we can see that silver nitrate has less mol than copper, therefore silver nitrate is the limiting reagent. We can find the theoretical yield of the experiment by calculation using the limiting reagent:

MAg = 1.045 AgNO3 x 1 mol AgNO3/169.8731 g AgNO3 x 2 mol Ag/2 mol AgNO3 x 107.8682 g Ag/1 mol AgNO3 = 0.66 g Ag

MCu(NO₃)₂ = 1.045 AgNO₃ x 1 mol AgNO₃/169.8731 g AgNO₃ x 1 mol Cu(NO₃)₂/2 mol Ag(NO₃)₂ x 187.5558 g Cu(NO₃)₂/1 mol Cu(NO₃)₂ = 0.57 g Cu(NO₃)₂

:: The calculation shows that the theoretical yield of the resulting silver is 0.66 g and the theoretical yield of the resulting copper nitrate is 0.57 g. If we found the theoretical yield we can found the percentage yield:

% of Ag = 1.84g Ag/066 g Ag x 100% = 279%

% of Cu(NO₃)₂ = 0.65 g Cu(NO₃)₂/ 0.57 g Cu(NO₃)₂ x 100% = 114%

Procedure:

1. Each group member had to put on safety clothing such as goggles, apron and latex gloves first, before starting the experiment.
2. Someone had to clean the materials including all the beakers, stirring rod, and wash bottle before using it, using water and brush (if necessary) and drying them with a clean tissue paper.
3. After cleaning all the materials needed, one member had to cut some copper wire about 12 inches long, and made sure that the copper wire was polished/smoothed using a sandpaper/ or tissue paper.
4. The mass of the copper wire was measured to the nearest 0.01g and recorded the data that has been collected.
5. The copper wire was coiled into loose coil and attached on a splint (or popsicle stick), and was tested not to touch any sides of the 100 ml beaker and the bottom as well.
6. The coiled wire was removed from the beaker after making sure that the it didn't touch any sides of the beaker.
7. About 1.00g or 1.40g of silver nitrate crystals had been taken and placed in the 100 ml beaker, with the help of the teacher, and the mass was recorded to the nearest 0.01g.
8. After recording the mass, a small volume of distilled water was added in the beaker. Somebody in the group stirred the silver nitrate crystals using a stirring rod to dissolve it.
9. After dissolving the crystals, the stirring rod was rinsed with a wash bottle using only 5 ml of distilled water (as close as possible) where the water has been collected with another beaker.
10. The distilled water used in rinsing the stirring rod was collected and mixed with the beaker that has silver nitrate solution in it.
11. After adding the water used in rinsing, more distilled water was added until the beaker was full by about 3 cm from the top.
12. The coiled copper wire, which was still attached in the splint ( or popsicle stick) , was added in the beaker with silver nitrate solution in it.
13. The beaker was covered by aluminum foil and was allowed to remain undisturbed overnight. Some observations were recorded.
14. The mass of two, clean, 250 ml beaker were measured and recorded to the nearest 0.01g.
15. The splint with copper wire was lifted and transferred from the 100 ml beaker to one of the 250 ml beaker, while making sure that the silver crystal deposits wouldn't fall during the process.
16. The silver deposits were removed from the copper wire using a stream of distilled water (as little amount as possible, trying not to exceed 25ml) into the beaker.
17. The copper wire was dried after the silver was removed from it. Then the mass of the dry copper wire was measured and recorded to the nearest 0.01g.
18. When the silver metals have already settled at the bottom of the 250 ml beaker, as much amount of water as possible had been decanted without losing any silver metals during the process. (In the process where the splint has to be transferred to the 250 ml beaker from the 100 ml beaker, if some silver metals had fallen or has been removed during the process, make sure to decant it as well and transfer the collected silver metals in the 250 ml beaker where the other silver metals are.)  NOTE: The decanting process is explained at the bottom of this page highlighted in red. 
19. The remaining silver metals, that were found along the sides of the beaker, were washed using small amount of distilled water. The distilled water used in washing the silver on the sides of the beaker was decanted as well.  
20. The silver was allowed to be air dried overnight.
21. When the silver had been dried, the mass of the silver residue in the beaker was measured to the nearest 0.01g and was recorded.
22. After the experiment, the workstation has been cleaned, all equipment used were washed and dried, and all the litters were put in the trash can.
21. Using the collected data, the percentage yield was calculated and posted in the website, Moodle, as directed by the teacher.

**DECANTING PROCESS:
                         This process is done by pouring off a liquid leaving the precipitate (the silver residue in this case) at the bottom of the container (beaker). This process can be done using the stirring rod where the liquid is allowed to flow through it so that the liquid will not flow rapidly, preventing too much silver to be lost.     
    

Title: Investigatioin 7.5.1
       What stopped the silver?
     Hana Amin, Bryan Jose, Avanti Peusangan

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