Question: Has anyone a good design for electro-magnets that actually works? It seems the designs in the texts are rather weak and not very effective. Answer: In order to have sufficient current passing through the wire, the wire must be rated to carry at least 3 amps. Wire of this thickness can cause the electromagnet…
Posts Tagged with Q&A
Chloroplasts:
Question: Does anyone know of a suitable water-plant for year 8s to be able to observe chloroplasts under the microscope? Answer: Use Valis (Vallisneria). Just pop it on a microscope slide, give it a little squash with your thumb and view. You don’t even need a cover slip and no stain. Just make sure you…
Chlorophyll chromatography
Question: What is the best solvent to use in the extraction of pigments from chlorophyll? We have tried ethanol, acetone and a 50/50 solution of the two, but the bands aren’t great. Answer: You can use 1:1 ethanol: petroleum ether to extract the pigments then 2 percent ethanol : 98 percent petroleum ether to separate…
Bench protectors/mats:
Here is some feedback on bench protectors: Masonite (hard board). The boards are not scorch resistant, but won’t scratch the benches, are light and easy to store. Masonite is available at Bunnings. Hardiflex, or fibro-cement purchased from Bunnings. It is available in 1800 x 1200 sheets and I cut it into 9 boards of 600…
Barium hydroxide:
Question: Why are we getting a precipitate when we mix barium chloride and sodium hydroxide solutions? Barium hydroxide is supposed to be soluble. Answer: Pure barium hydroxide is soluble (1.7 to 101.4 g / 100 mL at 0 to 80 degrees C) Mixing fresh solutions, you will not get a precipitate BUT sodium hydroxide slowly…
Vitamin C content of fruit:
Question: Does anyone have information on how to test the Vitamin C content of different fruits? Answer: We do a simple practical using 5 different juices: freshly squeezed orange juice, bottled 100 percent cordial, lemon juice and boiled orange juice as comparisons. You could also use grapefruit but note that if you were using, for…
Sherbet:
Question: Does anyone have a recipe for sherbet which includes jelly crystals please? Answer: I tried many recipes, and the winners are: First prize: icing sugar 1 tablespoon Bicarb soda (Sodium hydrogen carbonate) quarter teaspoon citric acid quarter teaspoon jelly crystals 1 teaspoon Second prize: Bicarb soda 1 teaspoon icing sugar 10 teaspoons citric acid…
Lemon Battery:
Question: Does anyone have any tips on how to make the lemon battery work? We are using Jacaranda Science Book 2, page 231. Answer: For best results with a lemon battery use BROAD pieces of zinc and copper (1-2cm wide, roughly polished with sandpaper). Use a high impedance meter (any digital multimeter) to monitor the…
Flame tests:
Question: Our text-book says to burn 2M solutions for flame tests, and I have tried solids too, but IT DOES NOT WORK! Can you please tell me what you do, and what actually works? Answer: Buy flame test bottles (atomisers) from Haines Educational. Use the following: All 0.5 M. Copper sulfate, sodium chloride, potassium chloride,…
Fingerprints-latent:
Question: Gentian Violet for fingerprinting is a banned substance now and is not procurable any more. Are there any alternatives? Answer: 1. On wood in silver nitrate. 2. Finger prints on filter paper in iodine chamber. Use a fume hood. Put fingerprints on filter paper and attach a paper clip and cotton thread to it,…