Reactivity of Alkali Metals in Water

The video demonstrates the reaction of alkali metals with water, focusing on sodium, lithium, and potassium. It begins with setting up the experiment, emphasizing the importance of safety measures. Sodium is prepared and introduced to water, showing its reaction and the resulting color change due to phenolphthalein. The video extends the demonstration to lithium and potassium, highlighting their reactivity and flame colors.

Why is it important to use cold water in the demonstration?

• To prevent the sodium from melting too quickly

• To ensure the reaction is visible

• To slow down the reaction

• To keep the indicator solution stable

What should be done if only one safety screen is available?

• Use a larger bowl

• Position it next to a wall

• Add more water

• Use a smaller piece of sodium

What is the purpose of using filter paper in the sodium demonstration?

• To prevent sodium from sinking

• To absorb excess water

• To stabilize the sodium

• To enhance the reaction

What is the characteristic flame color of sodium when it reacts with water?

• Green

• Lilac

• Orange-yellow

• Blue

What color does phenolphthalein turn in the presence of sodium hydroxide?

• Purple

• Green

• Blue

• Red

What is produced when sodium reacts with water?

• Sodium sulfate

• Sodium hydroxide

• Sodium carbonate

• Sodium chloride

What is the role of the indicator solution in the demonstration?

• To prevent the reaction

• To react with sodium

• To show the pH change

• To change the color of the water

Which alkali metal is less reactive than sodium but still reacts vigorously with water?

• Lithium

• Magnesium

• Potassium

• Calcium

Which alkali metal burns with a lilac flame?

• Rubidium

• Potassium

• Lithium

• Sodium

What happens to lithium when it reacts with water?

• It floats and bubbles

• It sinks

• It dissolves completely

• It catches fire