Acids and Alkalis: Understanding pH and Indicators

The video tutorial covers the basics of acids and alkalis, explaining their properties and how they interact in solutions. It introduces the pH scale, detailing how it measures acidity and alkalinity, and describes the use of indicators like litmus paper, methyl orange, and phenolphthalein to determine the pH of a solution. The tutorial also discusses the practical applications of these concepts, such as in titrations, to identify when a solution is neutralized.

What ions are formed when hydrochloric acid is dissolved in water?

• Positive chloride ions and negative hydrogen ions

• Positive hydroxide ions and negative sodium ions

• Positive sodium ions and negative hydroxide ions

• Positive hydrogen ions and negative chloride ions

Which pH value represents a neutral solution?

• pH 14

• pH 7

• pH 10

• pH 0

What happens to the pH value as the concentration of OH- ions increases?

• The pH value decreases

• The solution remains neutral

• The solution becomes more alkaline

• The solution becomes more acidic

What is the primary function of an indicator in a chemical solution?

• To change the temperature of the solution

• To increase the acidity of the solution

• To neutralize the solution

• To indicate the pH level by changing color

Which color does red litmus paper turn in an alkaline solution?

• Red

• Yellow

• Blue

• Green

What color does methyl orange turn in a basic solution?

• Red

• Yellow

• Blue

• Pink

If a solution turns phenolphthalein bright pink, what can be inferred about the solution?

• It is a strong acid

• It is alkaline

• It is neutral

• It is acidic