Careful Observations

Exercise N°1: Careful Observation

1st Report

Zg. Polskava, 7 September 2009

Aim

The aim of the experiment is to emphasize the importance of carefulness of the observations during experiments.

Experiments

1. Adding a few drops of silver nitrate solutions to a test tube containing 2 or 3 cm3 of sodium chloride solutions.

2. Dropping a provided piece of magnesium into a test tube containing 2 or 3 cm3 of dilute sulphuric acid.

3. Dropping the piece of zinc provided into 5 cm3 of copper(II) sulphate solution, warming the mixture and letting it stand for five minutes.

4. Heating a spatula measure of copper(II) carbonate in a test tube.

5. Adding a few drops of dilute hydrochloric acid to a test tube containing about 5 cm3 of sodium thiosulphate solution and letting the mixture stand for several minutes.

6. Heating a piece of magnesium ribbon in Bunsen flame, using tongs.

7. Mixing approximately 5cm3 of dilute hydrochloric acid with approximately 5 cm3 of sodium hydroxide solution in a test tube.

8. Heating half a spatula measure of ammonium chloride in a test tube.

Observations

|N° of Experiment |Changes |

|1 |white precipitate |

|2 |formation of bubbles |

|3 |turning brown, precipitation |

|4 |changing colour into black, foul odour |

|5 |becoming opaque, yellow |

|6 |white flame, substance turning to white powder |

|7 |becoming opaque |

|8 |sublimation |

Table 1: Changes in colour in different test tubes....