Properties of Acids

Properties of Acids

• Acids are liquids.
• Concentrated acids can be corrosive.
• Acids taste sour.
• Acids turn blue litmus paper red.
• Acids react with metals to form salts.
• Acids contain hydrogen ions.
• Acids turn Universal Indicator from green to red and have a pH less than 7.
• Examples of acids include vinegar (ethanoic acid) and lemon juice (citric acid).
• Common acids used in school laboratories include hydrochloric acid (HCl), nitric acid (HNO3), and sulphuric acid (H2SO4).

Properties of Alkalis

• Alkalis feel soapy to touch.
• Like acids, alkalis can burn the skin.
• Alkalis turn red litmus paper blue.
• Alkalis contain hydroxide ions (OH-).
• Alkalis taste bitter.
• Alkalis turn Universal Indicator from green to blue or purple.
• Common alkalis used in school laboratories include sodium hydroxide (NaOH), ammonia (NH3/NH4OH), and calcium hydroxide (Ca(OH)2).

Properties of Neutral Substances

• Litmus paper is not affected by neutral substances.
• Neutral substances tend to be harmless.
• Universal Indicator stays green in neutral substances.
• Examples of neutral substances include water, sodium chloride solution (NaCl), and sugar solution (C6H12O6).

Identifying Acidic or Alkaline Solutions

Litmus Paper Test

• Acidic solutions turn blue litmus paper red and keep red litmus paper red.
• Neutral solutions keep red litmus paper red and blue litmus paper blue.
• Alkaline solutions turn red litmus paper blue and keep blue litmus paper blue.

pH Scale and Indicators

• The strength of an acid or alkali is shown using a scale of numbers called the pH scale.
• The pH scale ranges from 0-14.
• Acidic solutions have a pH less than 7.
• Neutral solutions have a pH of 7.
• Alkaline solutions have a pH greater than 7.
• Universal indicator changes color depending on the pH of the solution.
• Universal indicator can be used to prepare homemade indicators from red cabbage or beetroot juice.

This quiz covers the characteristics and properties of acids, including their physical properties, chemical behavior, and examples of acids.