Acids and Alkalis Chemistry Notes

Acids and Alkalis

What are Acids?

  • (6-2)

Properties of Acids

  • Acids are corrosive.

  • Acids have a sour taste.

  • Acids are neutralized by bases, producing water and a salt.

Properties of an Acid (Summary)

  • Tastes sour

  • Conducts electricity

  • Turns blue litmus paper red

  • Reacts with certain metals to produce hydrogen gas

  • Corrosive

  • Reacts with an alkali to produce salt and water

What are Alkalis?

Properties of Bases

  • Alkalis are neutralized by acids, producing water and a salt.

Properties of an Alkali (Summary)

  • Tastes bitter

  • Conducts electricity

  • Turns red litmus paper blue

  • Soapy and slippery

  • Corrosive

  • Reacts with a dilute acid to produce salt and water

Hazard Symbols

  • Corrosive: Could burn the skin and damage the eyes. Avoid breathing in vapors.

  • Explosive: May explode when dry or exposed to heat or flames.

  • Flammable: May catch fire when exposed to oxygen and a heat source.

  • Harmful to the environment: Could cause damage to animal and plant life if released into water systems.

Indicators and the pH Scale

What is an Indicator?

  • Litmus paper and litmus solution are examples of indicators.

    • Litmus is red in acid.

    • Litmus is blue in alkali.

What is the pH Scale?

  • The strength of an acid or alkali is measured by the pH scale.

  • Each universal indicator color is given a number called the pH value.

  • Universal indicator can tell you the pH of a solution.

pH Values

  • pH of pure water: 7 (neutral)

  • pH scale ranges from 0 to 14.

  • pH < 7: acidic

  • pH > 7: alkaline

  • pH = 7: neutral

  • The lower the pH value, the stronger the acid.

  • The higher the pH value, the stronger the alkali.

  • Natural indicators are dye extracted from plant parts as pH indicators.

Glossary

  • Acid: A chemical that has a pH less than 7.

  • Alkali: A chemical that has a pH greater than 7 and dissolves in water.

  • Indicator: A special chemical that changes into different colours in acid and alkali solutions.

  • Neutral: A chemical with a pH of 7 that is not an acid or an alkali.

  • Neutralization: The chemical reaction between an acid and an alkali.

  • pH scale: The range of values that shows how strong or weak an acid or alkali is.

  • Universal indicator: The indicator that shows the pH value of a chemical.