Students have been given:
- Assessment task - Planning an experiment to test the best metals to use in a water fountain - see OneNote
- A scaffold detailed plan on how to tackle the writing of the task - see OneNote
- Marking sheet (plus ANALYSIS writing task - 250 words)
Reactivity of Metals tables show reaction of metals with water, acids, oxygen in air, but not salt. (Design an experiment to test 4-5 metals under different conditions for corrosion, including a salt solution).
Explain the effect of salt in water on corrosion rates. (Define a catalyst)
Information for the Science Understanding Introduction
Information for the suggested modification of experiment section
Notice this experiment shows many controlled variables, such as:
- all iron nails are identical (compare this with just testing different metals, different sample sizes and surface areas)
- conditions have been controlled to just air (cork seal and silica crystals in test-tube keep the tube water free); de-oxygenated (boiled) water sealed by a layer of oil from the chance of having access to oxygen in air; water with access to oxygen from air; salt water (salt is a catalyst and electrolyte to rusting). Compare this with how you did your own experiment)
- By controlling the conditions, the experiment can truly test which conditions speed up rusting. From the table of results one can see that both oxygen and water are requirements for rusting of iron to occur.