Safety and Testing in Chemistry

This video demonstrates a positive test for nitrate ions using aluminium powder and sodium hydroxide. The process involves adding these to a calcium nitrate solution, optionally using Devarda's alloy for a faster reaction. The solution is gently heated, with safety precautions to prevent bumping. The test concludes by using damp red litmus paper to detect the gas produced, indicating a positive result when the paper turns blue.

What is added to the solution of calcium nitrate in the initial steps of the test?

• Potassium permanganate

• Dilute sodium hydroxide

• Hydrochloric acid

• Concentrated sulfuric acid

What is Devarda's alloy composed of?

• Aluminum, magnesium, and zinc

• Iron, copper, and nickel

• Aluminum, copper, and zinc

• Copper, zinc, and tin

Why should the solution be heated gently by passing the test tube slowly in and out of the flame?

• To mix the solution thoroughly

• To ensure the solution reaches boiling point quickly

• To prevent the solution from evaporating

• To avoid the formation of steam bubbles that can blow the contents out

What safety precaution should be taken when testing the gas with damp red litmus paper?

• Use a glass rod

• Avoid breathing in the fumes

• Keep the test tube in ice

• Wear safety goggles

What indicates a positive test for nitrate ions?

• The gas produced has no smell

• The solution forms a precipitate

• The damp red litmus paper turns blue

• The solution turns green