Families of Elements
October 21, 2008
Families of Elements Laboratory
Elements in the same family will combine in the same ratio with ions of the same charge. They will also exhibit similar properties such as color, solubility etc. In this lab we will combine several compounds that have negative ions in the same family and one negative ion will be of another family. Look for a different ratio of ions and different properties of the precipitate.
Procedures:
1) Take the large plastic bottle labeled Silver nitrate (AgNO3) and place one drop of the solution in well number 1, two drops in well number 2, 3 in well 3,…. Till you come to well number 11 and place 11 drops of AgNO3 in it. Then starting with well number 11 add 1 drop of potassium iodide (KI), then 2 drops into well #10, 3 drops in well #9, 4 drops in well #8… till finally you put 11 drops into well number 1. Each well will now have 12 drops total.
2) Observe the wells. Write your observations into the data table. The well that has the most precipitate will be the well that has the closest ratio of ions to combine together. Using this information determine the ratio of ions in the compound.
Example: If well #4 had the most precipitate, with 4 drops of AgNO3 and 8 drops of KI, the ratio of ions would be 1 of AgNO3 to 2 of KI, making the formula for the compound, AgI2. Or if well #6 had the most precipitate then, 6 drops of AgNO3 to 6 drops of KI, then the ratio would be 1 to 1 and the formula would be AgI.
3) Rinse out the well plate and dry with paper towel
4) Repeat steps 1 , 2, and 3 with the other three solutions, potassium chloride, potassium bromide and potassium sulfide with the silver nitrate for a total of four trials. Record your observations in the data table.
5) Wash your hands and clean up your lab area after you finish. Several of the compounds are toxic or will turn your hands black. Be Careful.
Data Table:
|
Positive Ion (Ag) |
Negative Ion |
Observation |
Ratio of drops |
Chemical formula |
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AgNO3 |
Potassium Iodide |
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AgNO3 |
Potassium Chloride |
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AgNO3 |
Potassium Bromide |
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AgNO3 |
Potassium sulfide |
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Questions:
1) Which negative ion is in a different family and how could you tell from your data?
2) What happened to the other ions?
3) Why do families of elements exhibit these traits?
4) Could you do this experiment using families of positively charged ions?
Conclusion:
- What did you learn?
- Why did things happen?
- Problems?
- Improvements?
Families of Elements Laboratory
October 21, 2008
Families of Elements Laboratory
Elements in the same family will combine in the same ratio with ions of the same charge. They will also exhibit similar properties such as color, solubility etc. In this lab we will combine several compounds that have negative ions in the same family and one negative ion will be of another family. Look for a different ratio of ions and different properties of the precipitate.
Procedures:
1) Take the large plastic bottle labeled Silver nitrate (AgNO3) and place one drop of the solution in well number 1, two drops in well number 2, 3 in well 3,…. Till you come to well number 11 and place 11 drops of AgNO3 in it. Then starting with well number 11 add 1 drop of potassium iodide (KI), then 2 drops into well #10, 3 drops in well #9, 4 drops in well #8… till finally you put 11 drops into well number 1. Each well will now have 12 drops total.
2) Observe the wells. Write your observations into the data table. The well that has the most precipitate will be the well that has the closest ratio of ions to combine together. Using this information determine the ratio of ions in the compound.
Example: If well #4 had the most precipitate, with 4 drops of AgNO3 and 8 drops of KI, the ratio of ions would be 1 of AgNO3 to 2 of KI, making the formula for the compound, AgI2. Or if well #6 had the most precipitate then, 6 drops of AgNO3 to 6 drops of KI, then the ratio would be 1 to 1 and the formula would be AgI.
3) Rinse out the well plate and dry with paper towel
4) Repeat steps 1 , 2, and 3 with the other three solutions, potassium chloride, potassium bromide and potassium sulfide with the silver nitrate for a total of four trials. Record your observations in the data table.
5) Wash your hands and clean up your lab area after you finish. Several of the compounds are toxic or will turn your hands black. Be Careful.
Data Table:
|
Positive Ion (Ag) |
Negative Ion |
Observation |
Ratio of drops |
Chemical formula |
|
AgNO3 |
Potassium Iodide |
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AgNO3 |
Potassium Chloride |
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AgNO3 |
Potassium Bromide |
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AgNO3 |
Potassium sulfide |
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Questions:
1) Which negative ion is in a different family and how could you tell from your data?
2) What happened to the other ions?
3) Why do families of elements exhibit these traits?
4) Could you do this experiment using families of positively charged ions?
Conclusion:
- What did you learn?
- Why did things happen?
- Problems?
- Improvements?
Isotopes of Pennium
October 7, 2008
Isotopes of “Pennium” Pre-lab Questions: (leave room for answers)1) What do the pennies represent in this investigation?2) What do the different masses of the pennies represent?3) What information do you need to calculate the average atomic mass for an element? Procedures:1) Remove pennies from the baggie and make sure that you have twenty pennies. Record the number of the bag.2) Record the combined mass of all twenty pennies.3) Find the mass of each penny separately. In the data table, record the year the penny was minted and the mass to the nearest 0.02 gram.4) Return the pennies to their bag and return the pennies and the balance to your teacher Data: Number of the bag of Pennies ____________________ Combined Mass of pennies (to the nearest 0.02 gram) ________
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Penny |
Year |
Mass (grams) |
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1 |
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2 |
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3 |
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4 |
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5 |
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6 |
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7 |
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8 |
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9 |
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10 |
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11 |
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12 |
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13 |
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14 |
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15 |
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16 |
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17 |
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18 |
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19 |
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20 |
Calculations:1) Inspect your data carefully. Determine the number of isotopes of “pennium” that are present. (An isotope must have a difference in mass of at least 0.2 grams)2) Calculate the relative abundance of each isotope in your sample.3) Calculate the average atomic mass of each isotope.4) Using the relative abundance in #2 and the average atomic mass in #3, calculate the atomic mass of “pennium”. Critical thinking:1) Was the mass of 20 pennies equal to 20 times the mass of one penny? Explain.2) In what year(s) did the mass of pennium change? How could you tell? Conclusion: What did you learn? Why do the pennies make a good substitute for atoms? Problems? Improvements?
