6 Questions
What is the primary function of an indicator?
To indicate the presence of an acid or base
What is the pH of a neutral solution?
pH 7
Which of the following is an example of a natural indicator?
Cabbage juice
What is the effect of pH on the availability of nutrients in soil?
pH affects the availability of nutrients
What is the formula for calculating pH?
pH = -log[H+]
What is an example of a strong acid?
Stomach acid
Study Notes
Indicators
- Substances that change color in response to changes in pH
- Used to indicate the presence of an acid or base
- Can be natural or synthetic
- Examples of natural indicators:
- Litmus (derived from lichens)
- Turmeric (turns yellow in acidic solutions and orange in basic solutions)
- Cabbage juice (turns pink in acidic solutions and green in basic solutions)
- Examples of synthetic indicators:
- Phenolphthalein (turns pink in basic solutions)
- Methyl orange (turns yellow in acidic solutions and orange in basic solutions)
pH Scale
- A scale used to measure the acidity or basicity of a solution
- pH ranges from 0 to 14
- pH 7 is neutral (neither acidic nor basic)
- pH below 7 is acidic
- pH above 7 is basic
- pH can be calculated using the formula: pH = -log[H+]
- Strong acids and bases have a pH close to 0 or 14, respectively
- Weak acids and bases have a pH closer to 7
pH Ranges
- Acidic: pH 0-6.9
- Examples: vinegar, stomach acid, lemon juice
- Neutral: pH 7
- Examples: water, blood
- Basic: pH 7.1-14
- Examples: soap, bleach, baking soda
Importance of pH
- pH affects the availability of nutrients in soil
- pH affects the activity of enzymes in biological systems
- pH affects the solubility of minerals
- pH is important in industrial processes, such as manufacturing and wastewater treatment
Indicators
- Substances that change color in response to changes in pH, used to indicate the presence of an acid or base
- Can be natural or synthetic
- Natural indicators include:
- Litmus, derived from lichens
- Turmeric, turns yellow in acidic solutions and orange in basic solutions
- Cabbage juice, turns pink in acidic solutions and green in basic solutions
- Synthetic indicators include:
- Phenolphthalein, turns pink in basic solutions
- Methyl orange, turns yellow in acidic solutions and orange in basic solutions
pH Scale
- A scale used to measure the acidity or basicity of a solution
- pH ranges from 0 to 14
- pH 7 is neutral, neither acidic nor basic
- pH below 7 is acidic
- pH above 7 is basic
- pH can be calculated using the formula: pH = -log[H+]
- Strong acids and bases have a pH close to 0 or 14, respectively
- Weak acids and bases have a pH closer to 7
pH Ranges
- Acidic: pH 0-6.9
- Examples include vinegar, stomach acid, and lemon juice
- Neutral: pH 7
- Examples include water and blood
- Basic: pH 7.1-14
- Examples include soap, bleach, and baking soda
Importance of pH
- pH affects the availability of nutrients in soil
- pH affects the activity of enzymes in biological systems
- pH affects the solubility of minerals
- pH is important in industrial processes, such as manufacturing and wastewater treatment
Learn about substances that change color in response to changes in pH, used to indicate the presence of an acid or base. Discover natural and synthetic indicators, including litmus, turmeric, and phenolphthalein.
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