silver alloy lab
Ap Chem. Period 7
9/14/2014
Analysis of Silver in an Alloy
Purpose- To determine silver content of an alloy and to calculate the percent silver in the alloy.
Materials
Chemicals
•Silver-Copper Alloy
•Nitric Acid (NHO3)
•Baking Soda (NaHCO3)(s)
•Sodium Chloride (NaCl)(s)
Equipment
•Beakers, 100 and 250 mL
•Filter Flask and Walter's adapter
•Stirring Rod
•Wash Bottle
•Watch Glass
•Crucible Tongs
•Ring Stand, Ring, Wire gauze
•Bunsen Burner
•Graduated Cylinder
•Rubber or Plastic Policeman
•Drying Oven
•Fume Hood
•Sensitive Balance
•Paraflim
•Gooch Crucible
Procedure
1) Prepare a filter Crucible - Clean the Crucible and put it in oven to let it dry, once dry put the crucible on a sensitive balance to find mass.
2) Find mass of the alloy between .1- .5 grams
3) Dissolve the silver - Put the silver alloy and 20 mL of nitric acid (NHO3) in clean 100 mL beaker, place the watch glass on top for splatter protection.
4) Weigh out two times the amount of sodium chloride and dissolve it in 25 mL distilled water and add it to the solution of Alloy and Nitric acid (NHO3) and stir.
5) Add 2 mL of Nitric acid ((NHO3) to keep the particles from peptizing, then pour the solution into crucible.
6) Dry the crucible in an oven at 110 degrees Celsius for at least 30 minutes.
7) From the data determine percent of silver in sample.
Data and Observations Mass of Ag - .2240 grams Mass of NaCl - .2573 grams
Initial Mass of Gooch - 23.5707 grams
New Mass Of Gooch - 23.8371 grams
QuestionsTop of Form
1) Show Calculations
2) Why is twofold excess of chloride added to precipitate he silver? It ensures that all of the Ag is precipitated and nothing lost.
3) Why don’t you have to weigh the sodium chloride on a sensitive balance?
You don't have to weigh the sodium 4 numbers past decimal because as long as you have an excess of NaCl to get enough Cl ions to precipitate all of the silver ions. So no accurate balance needed
4) Why
9/14/2014
Analysis of Silver in an Alloy
Purpose- To determine silver content of an alloy and to calculate the percent silver in the alloy.
Materials
Chemicals
•Silver-Copper Alloy
•Nitric Acid (NHO3)
•Baking Soda (NaHCO3)(s)
•Sodium Chloride (NaCl)(s)
Equipment
•Beakers, 100 and 250 mL
•Filter Flask and Walter's adapter
•Stirring Rod
•Wash Bottle
•Watch Glass
•Crucible Tongs
•Ring Stand, Ring, Wire gauze
•Bunsen Burner
•Graduated Cylinder
•Rubber or Plastic Policeman
•Drying Oven
•Fume Hood
•Sensitive Balance
•Paraflim
•Gooch Crucible
Procedure
1) Prepare a filter Crucible - Clean the Crucible and put it in oven to let it dry, once dry put the crucible on a sensitive balance to find mass.
2) Find mass of the alloy between .1- .5 grams
3) Dissolve the silver - Put the silver alloy and 20 mL of nitric acid (NHO3) in clean 100 mL beaker, place the watch glass on top for splatter protection.
4) Weigh out two times the amount of sodium chloride and dissolve it in 25 mL distilled water and add it to the solution of Alloy and Nitric acid (NHO3) and stir.
5) Add 2 mL of Nitric acid ((NHO3) to keep the particles from peptizing, then pour the solution into crucible.
6) Dry the crucible in an oven at 110 degrees Celsius for at least 30 minutes.
7) From the data determine percent of silver in sample.
Data and Observations Mass of Ag - .2240 grams Mass of NaCl - .2573 grams
Initial Mass of Gooch - 23.5707 grams
New Mass Of Gooch - 23.8371 grams
QuestionsTop of Form
1) Show Calculations
2) Why is twofold excess of chloride added to precipitate he silver? It ensures that all of the Ag is precipitated and nothing lost.
3) Why don’t you have to weigh the sodium chloride on a sensitive balance?
You don't have to weigh the sodium 4 numbers past decimal because as long as you have an excess of NaCl to get enough Cl ions to precipitate all of the silver ions. So no accurate balance needed
4) Why