17 Questions
What is the pH of a neutral substance like pure water?
7
What is the purpose of an indicator in measuring pH?
To change color depending on the pH
What is the definition of an acid?
A substance with a pH of less than 7
What is the term for the subgroup of bases that are soluble in water?
Alkalis
What is the pH of stomach acid?
2
What is the function of a pH probe connected to a pH meter?
To provide an electronic, numerical reading of the pH
What is the pH of washing-up liquid?
9
What is the result of combining hydrogen ions from an acid and hydroxide ions from a base?
Water and salt
What is the approximate pH range of acid rain?
pH 4-5
What type of substance has a pH of less than 7?
Acid
What is the pH of a solution with an equal concentration of hydrogen and hydroxide ions?
Exactly 7
What is the purpose of using a wide-range indicator?
To measure the pH of a solution over a wide range
What is the result of reacting an acid with a base?
A salt and water
What type of ion is formed when an alkali dissolves in water?
Hydroxide ion (OH-)
What is the term for the process of combining hydrogen ions from an acid and hydroxide ions from a base?
Neutralization
What is the purpose of using a pH meter?
To provide an electronic, numerical reading of the pH
What is the characteristic of a substance with a pH of exactly 7?
It is neutral
Study Notes
pH Scale
- pH measures the acidity or alkalinity of a solution, ranging from 0 (most acidic) to 14 (most alkaline)
- Neutral substances, like pure water, have a pH of 7
- Examples of acidic substances: stomach acid (pH 2), acid rain (pH 4)
- Examples of alkaline substances: washing-up liquid (pH 9), bleach (pH 12)
Measuring pH
- Indicators are chemical dyes that change color depending on the pH
- Different indicators change color at different pH
- Wide-range indicators, like universal indicator, change color across a wide pH range
- pH probes connected to pH meters provide an electronic, numerical reading of the pH
Acids and Bases
- Acids are substances that form aqueous solutions with a pH of less than 7
- Acids release hydrogen ions in water, making the solution acidic
- Bases are substances with a pH greater than 7
- Alkalis are a subgroup of bases that are soluble in water, forming solutions with a pH greater than 7
- Alkalis form hydroxide ions (OH-) in water
Neutralization Reactions
- Reacting an acid and a base produces a salt and water
- Examples: hydrochloric acid + sodium hydroxide → sodium chloride + water
- Hydrogen ions (H+) from the acid and hydroxide ions (OH-) from the base combine to form water (H2O)
- The pH of the products is neutral (pH 7) since the acid and base are neutralized
Common Acids and Bases
- Common acids: hydrochloric acid, sulfuric acid, nitric acid
- Common bases: hydroxides (sodium hydroxide) and carbonates (calcium carbonate)
pH Scale
- pH ranges from 0 (most acidic) to 14 (most alkaline)
- Neutral substances have a pH of 7
- Acidic substances: stomach acid (pH 2), acid rain (pH 4)
- Alkaline substances: washing-up liquid (pH 9), bleach (pH 12)
Measuring pH
- Indicators: chemical dyes that change color depending on pH
- Different indicators change color at different pHs
- Wide-range indicators: universal indicator, change color across a wide pH range
- pH probes: connected to pH meters, provide electronic, numerical reading of pH
Acids and Bases
- Acids: substances with pH < 7, release hydrogen ions in water, making solution acidic
- Bases: substances with pH > 7
- Alkalis: subgroup of bases, soluble in water, forming solutions with pH > 7
- Alkalis form hydroxide ions (OH-) in water
Neutralization Reactions
- Reacting acid and base produces salt and water
- Acid + base → salt + water (e.g., hydrochloric acid + sodium hydroxide → sodium chloride + water)
- Hydrogen ions (H+) from acid and hydroxide ions (OH-) from base combine to form water (H2O)
- Neutral pH (pH 7) of products due to neutralization of acid and base
Common Acids and Bases
- Common acids: hydrochloric acid, sulfuric acid, nitric acid
- Common bases: hydroxides (sodium hydroxide), carbonates (calcium carbonate)
pH Scale
- pH ranges from 0 (most acidic) to 14 (most alkaline)
- Neutral substances have a pH of 7
- Acidic substances: stomach acid (pH 2), acid rain (pH 4)
- Alkaline substances: washing-up liquid (pH 9), bleach (pH 12)
Measuring pH
- Indicators: chemical dyes that change color depending on pH
- Different indicators change color at different pHs
- Wide-range indicators: universal indicator, change color across a wide pH range
- pH probes: connected to pH meters, provide electronic, numerical reading of pH
Acids and Bases
- Acids: substances with pH < 7, release hydrogen ions in water, making solution acidic
- Bases: substances with pH > 7
- Alkalis: subgroup of bases, soluble in water, forming solutions with pH > 7
- Alkalis form hydroxide ions (OH-) in water
Neutralization Reactions
- Reacting acid and base produces salt and water
- Acid + base → salt + water (e.g., hydrochloric acid + sodium hydroxide → sodium chloride + water)
- Hydrogen ions (H+) from acid and hydroxide ions (OH-) from base combine to form water (H2O)
- Neutral pH (pH 7) of products due to neutralization of acid and base
Common Acids and Bases
- Common acids: hydrochloric acid, sulfuric acid, nitric acid
- Common bases: hydroxides (sodium hydroxide), carbonates (calcium carbonate)
Learn about the pH scale, measuring acidity and alkalinity, and how indicators are used to determine pH levels.
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