Notes

Silver nitrate solution is clear- copper formed cu(no3)2 to make a blue solution- produces no2
What’s the equation??
Concentrated acid:Ag + 2HNO3 --> AgNO3 + NO2 + H2O
Dilute Acid: 2Ag + 3HNO3 --> 2AgNO3 + HNO2 + H2O
https://answers.yahoo.com/question/index?qid=20071218133113AAa89Mt

Concentrated Acid: Ag(s)+2HNO3(aq) ----> 4AgNO3(l)+ NO2(g)+H2O (l)
Dilute Acid: 3Ag(s)+4HNO3(aq) ----> 3AgNO3(l)+NO(g)+2H2O (l)
Combined Equation??: 4Ag(s)+6HNO3(aq) ----> 3AgNO3(l)+NO(g) + NO2(g)+ 3H2O (l)
https://www.quora.com/What-chemical-equation-shows-that-silver-reacts-with-nitric-acid-HNO3-to-form-nitrogen-monoxide-NO-silver-nitrate-AgNO3-and-water





Materials:
Stirring rod, weigh boat, funnel, 0.475g filter paper, 100 mL glass beaker, 125 mL erlenmeyer flask, about ¼ silver dime 0.934g, test tube, water, 1.094g salt, scale, 6 M HCl

Data:
Mass of dime: 0.934 g
Filter paper: 0.475 g
Precipitate + filter paper: 1.582 g
Precipitate: 1.107 g

Hypothesis: Actual makeup of a 1945 dime: 90% silver, 10% copper
http://cointrackers.com/coins/148/1945-mercury-dime/

Calculations:

HNO3: (assume 90% Ag)
0.934g dime X (9 g Ag/ 10 g dime) X (1 mole Ag/ 107.9g Ag) X (1 mole HNO3(aq)/ 1 mole Ag) X (1L HNO3(aq) / 6 moles HNO3) X (1000 mL/ 1 L) = 1.30 mL X 2 = 2.60mL HNO3(aq)

2.60 mL HNO3(aq)
NaCl:
0.00866 moles Ag X (1 mole NaCl/ 1 mole Ag) X (58.5g/ 1 mole NaCl) X 2 = 1.01g NaCl

1.01g NaCl
Expected ppt:
0.934 g dime X ( 9.00 g silver/ 10.0 g dime) X (1 mole Ag/ 107.9 g Ag) X (1 mole AgCl/ 1 mole Ag) X ( 143.3 g AgCl/ 1 mole AgCl)= 1.12 g AgCl

1.12 g AgCl

Ag:
1.107g AgCl X (1 mole/ 143.3g) X (1 mole Ag/ 1 mole AgCl) X (107.9g/ 1 mole) = 0.8335g Ag

0.8335g Ag
Percent Ag:
Total mass = mass Ag + mass Cu
0.934g = 0.8335g Ag + mass Cu
Mass Cu = 0.101g

0.101g Cu

% Ag = mass Ag/ (mass Ag + mass Cu)
% Ag = 0.8335g Ag/ (0.8335g Ag + 0.101g Cu)

89.2% Ag by mass

Percent Error:
% error = (theoretical % - experimental %)/ theoretical %
% error = 0.80/ 90.

0.01% error


List of stuff:
Title
Names, dates, period
Purpose?
Hypothesis (what and why)- 1945 dime, 90% silver, 10% copper source; http://cointrackers.com/coins/148/1945-mercury-dime/
Background
Equations: 3Ag(s)+4HNO3(aq) ----> 3AgNO3(aq)+NO(g)+2H2O (l)
Cu + 4HNO3(aq) ----> Cu(NO3)2 (aq)+ 2NO2(g)+ 2H2O (l)
2NO(g) + O2 (g)----> 2NO2(g)
AgNO3(aq)+ NaCl(s)----> NaNO3(aq)+ AgCl(s)
Stoichiometry def: Stoichiometry, or literally translated “the measure of elements” is the process of finding relationships between quantity of reactants and quantity of products. Stoichiometry is an important tool for many reasons. It enables one to get exactly the right amount of product as well as know in what ratios the reactants must be in. This knowledge is used readily in many manufacturing industries to reduce waste of unnecessary amounts of chemicals.
History of coinage: http://www.ancient.eu/coinage/ The use of coins began around 400- 500 BCE and, although becoming more obsolete in modern society, has nevertheless been an important form of currency ever since. As times change, coins must change as well. At first, coins were often made of precious metals like gold and silver, but because people have taken natural resources from the ground for many years and materials such as precious metals are less accessible, coins must reflect the new prices. If the metal of the coins are more valuable than the number on the coin, people will start melting them down as they did with pennies in the 80’s.
Materials:
~ 1/4 of a 1945 dime
~ 2.88 mL 6M HNO3(aq)
Glass test tube
Non airtight plastic wrap
100 mL glass beaker
Stirring rod
Distilled water
1.094g NaCl
Funnel
0.475g filter paper
125 mL Erlenmeyer flask
Scale (to four decimals)
List of procedure
Day 1
First, we weighed the partial coin.
Next, we calculated the amount of nitric acid needed assuming that the coin was 90% silver.
We doubled that number and added the acid and the coin into the glass test tube.
Lastly, we sealed the test tube with non air tight wrap and let it react for 3 days.
Day 2
After removing the wrap and making observations, we emptied the blue solution into the 100 mL glass beaker.
We then calculated the amount of salt needed, multiplying that by two as well.
After, we weighed the dry filter paper.
We dissolved the salt in distilled water
Then, we combined the two solutions and mixed using the stirring rod for approximately 3 minutes.
Folding the filter to fit inside the funnel, we placed the funnel on the 125 mL Erlenmeyer flask.
After, we poured in the solution a little at a time, making sure that the water level was always below the filter line. We used distilled water to remove as much of the precipitate out of the beaker as possible.
Lastly, we put the contents of the flask into a chemical waste container and washed out the flask. Then we let the water evaporate off the filter paper for two days.
Day 3
We weighed the precipitate with the filter paper and subtracted the mass of the filter paper to find the mass of the precipitate.
Using the mass of the precipitate, we calculated the moles of AgCl and, using that, calculated the mass of Silver in the coin.
Data:

Data:
Silver Dime
NaCl
Precipitate with filter
Filter Paper
Precipitate
Measurement
0.934g
1.094g
1.582g
0.475g
1.107g
Observations
1. When added to nitric acid solution turned blue in color
2. Brown gas released after ~ 30 seconds in, subsided to clear after 2 days
3. When cover was removed space over solution became brown again.
1. Added to solution made white precipitate, cotton like in appearance
2. Solution leftover retained blue color
1. Solution was slow to move through filter, left behind white precipitate
2. When removing precipitate some remained on glass
1. Measured before the tear in corner was made
1. Taken by subtracting
2. White, crusty, salt like yet in bigger crystals, easier to move then evaporated NaCl

Results

Results:
Nitric acid needed
NaCl needed
Expected mass ppt
Total amount of silver (g)
Total amount of copper
% Ag by mass
% error
Answer
2.60mL
1.01g
1.12 g
0.8335 g
0.101g
89.2%
0.01%

Error Analysis
Talk about not weighing the filter paper with the notch ripped out- DO NOT SAY THAT WE WEIGHED THE OTHER PAPER
Talk about still having precipitate stuck to the beaker
Analysis
Discuss what happens to excess acid and salt
Inexact amount
Why nitric acid
Precipitate- why it formed
Wash precipitate?
Dry precipitate
Discuss yield
What happens to the copper
Forms Cu(NO3)2 (aq) which is soluble, evidence is the blue color, does not react with NaCl because nothing would precipitate + evidence is the blue color
Conclusion
Summarize results. Restate purpose and comment on fulfillment, confirm/ refute hypothesis, make connection to life application ???

*Note: double space, 12 pt font, have a title, order