Review the key concepts, formulae, and examples before starting your quiz.
🔑Concepts
Indicators are special substances that change their color when added to a solution containing an acidic or a basic substance. Red rose petals serve as a natural indicator.
Preparation: Red rose indicator is prepared by placing red rose petals in warm water and allowing them to sit until the water becomes colored.
Acidic Solutions: When the red rose indicator is added to an acidic substance (containing ions), it changes its color to dark pink or magenta.
Basic Solutions: When the red rose indicator is added to a basic substance (containing ions), it changes its color to green.
Neutral Solutions: In neutral substances like distilled water (), the indicator remains the same color or shows no significant change.
The process of mixing an acid and a base to nullify each other's effect is called Neutralization, represented by: .
📐Formulae
💡Examples
Problem 1:
A student tests a sample of Lemon juice using a red rose indicator. What color change will be observed?
Solution:
The solution will turn dark pink (magenta).
Explanation:
Lemon juice contains citric acid. Since red rose indicator turns dark pink in the presence of an acid (), the color change confirms the acidic nature of lemon juice.
Problem 2:
Identify the color change when red rose indicator is added to a solution of Baking Soda ().
Solution:
The solution will turn green.
Explanation:
Baking soda is a basic substance. Natural indicators like red rose petals react with bases ( ions) to produce a green color.
Problem 3:
What happens to the color of the red rose indicator when it is added to a solution of Common Salt ()?
Solution:
No color change is observed.
Explanation:
Common salt () is a neutral substance formed by the neutralization of a strong acid () and a strong base (). Indicators do not change color in neutral media.