A Fatty Acid Monolayer: Determination of Avogadro's Constant
Ngoc Pham
Chem162B
Lab #2: Trends in Periodic Table
Date: 01/10/2011
Lab partner: Ian Bauer
Result Section:
Table I: The solubility of the alkaline earth metal ions | SO42- | CO32- | C2O42- | IO32- | Mg2+ | S | I | S | S | Ca2+ | I | S | S | I | Sr2+ | S | S | S | I | Ba2+ | I | I | I | S |
Key: I- insoluble, S-soluble
Table II: Color of water (Halide) and Halogen (Hexane) layers | Cl2 | Br2 | I2 | Hexane layer | Clear | orange | Pink | Water layer | Clear, colorless | Light gold | Light yellow |
Table III: Reactivity of Halogen/Halide Combinations | Cl- | Br- | I- | Cl2 | X | R | R | Br2 | NR | X | R | I2 | NR | NR | X |
Key: R-reaction occurred, NR-no reaction occurred, X-not tested (there should be no reaction)
The redox reactions took place:
Cl2 (aq) + 2Br-(aq) → Cl-(aq)+ 2Br2(aq)
Cl2 (aq) + 2I-(aq)→ Cl-(aq)+ 2I2(aq)
Br2 (aq) + 2I-(aq)→ Br-(aq)+ 2I2(aq)
Answer questions:
Part A 1. Ba2+ > Sr2+ > Ca2+ > Mg2+
2. The ranking above does show a trend in the periodic table. Ba2+ forms the most precipitates in the experiment and shows up on the bottom of the period table, while Mg2+ forms the least precipitates and therefore listed at the top, above the other cations.
3. Atomic size for cation trend: Because Ba2+ atomic size is increasing. It is larger when going down the column. So Ba2+ will be less soluble than Sr2+, Ca2+, and Mg2+. The bigger size (cation ionic size) makes Ba2+more difficult to soluble for solubility depends on hydration of cation (enthalpy of solution) → more precipitates.
Part B 4. According to the procedure, we are supposed to look at the color that is seen in the hexane layer. A reaction is indicated if the final hexane color shows presence of a halogen other than the initial. So the data shown in the C l-/ Br2 box shows a dark orange color which means there was not reaction, while the box Br-, Cl2 shows reaction did occur. This means Chloride must be a
Chem162B
Lab #2: Trends in Periodic Table
Date: 01/10/2011
Lab partner: Ian Bauer
Result Section:
Table I: The solubility of the alkaline earth metal ions | SO42- | CO32- | C2O42- | IO32- | Mg2+ | S | I | S | S | Ca2+ | I | S | S | I | Sr2+ | S | S | S | I | Ba2+ | I | I | I | S |
Key: I- insoluble, S-soluble
Table II: Color of water (Halide) and Halogen (Hexane) layers | Cl2 | Br2 | I2 | Hexane layer | Clear | orange | Pink | Water layer | Clear, colorless | Light gold | Light yellow |
Table III: Reactivity of Halogen/Halide Combinations | Cl- | Br- | I- | Cl2 | X | R | R | Br2 | NR | X | R | I2 | NR | NR | X |
Key: R-reaction occurred, NR-no reaction occurred, X-not tested (there should be no reaction)
The redox reactions took place:
Cl2 (aq) + 2Br-(aq) → Cl-(aq)+ 2Br2(aq)
Cl2 (aq) + 2I-(aq)→ Cl-(aq)+ 2I2(aq)
Br2 (aq) + 2I-(aq)→ Br-(aq)+ 2I2(aq)
Answer questions:
Part A 1. Ba2+ > Sr2+ > Ca2+ > Mg2+
2. The ranking above does show a trend in the periodic table. Ba2+ forms the most precipitates in the experiment and shows up on the bottom of the period table, while Mg2+ forms the least precipitates and therefore listed at the top, above the other cations.
3. Atomic size for cation trend: Because Ba2+ atomic size is increasing. It is larger when going down the column. So Ba2+ will be less soluble than Sr2+, Ca2+, and Mg2+. The bigger size (cation ionic size) makes Ba2+more difficult to soluble for solubility depends on hydration of cation (enthalpy of solution) → more precipitates.
Part B 4. According to the procedure, we are supposed to look at the color that is seen in the hexane layer. A reaction is indicated if the final hexane color shows presence of a halogen other than the initial. So the data shown in the C l-/ Br2 box shows a dark orange color which means there was not reaction, while the box Br-, Cl2 shows reaction did occur. This means Chloride must be a