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Acids and bases

Acids and bases. Acids & bases. Why do vinegar or lemon juice taste sour? They are Acids! The term acid comes from the Latin term acere , which means “sour” In the 17 th century, chemist Robert Boyle first labeled substances as acids or bases according to certain characteristics.

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Acids and bases

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  1. Acids and bases

  2. Acids & bases • Why do vinegar or lemon juice taste sour? • They are Acids! • The term acid comes from the Latin term acere, which means “sour” • In the 17th century, chemist Robert Boyle first labeled substances as acids or bases according to certain characteristics. • 1st reasonable definition for acids and bases was not proposed until the 19th century, with Swedish scientist Svante Arrhenius

  3. arrhenius • Stated that Acids contained Hydrogen and release hydrogens into solution • Bases release OH- (Hydroxide Ions) into solution. • Acids and Bases can combine to neutralize, or counteract each other.

  4. Acids • Acids in the home • Dilute weak acids • Have a sour taste • Safe to use in food, but can still hurt if they get into a cut or eyes • Examples • Vinegar = Ethanoic Acid • Fizzy Drinks (Soda) = Carbonic Acid • Tea = Tannic Acid • Vitamin C = Ascorbic Acid • Lemons = Citric Acid

  5. Bases • React with oils and fats • Often used in strong household cleaners • Examples • Drain cleaners and oven cleaners contain Sodium Hydroxide • Ammonia is also used in cleaners • Wise to wear gloves with these substances because it will burn skin! • Weak bases are found in toothpaste, antacid tablets (help to cure an upset stomach) and baking powder

  6. Indicators and the ph scale • Indicator: substance that can change color when they are added to acidic or alkaline/basic solutions • You can prepare your own homemade indicators • Two commonly used indicators • Litmus paper • Universal indicator

  7. Litmus Paper

  8. Universal indicator • Is a mixture of several different indicators • It shows us EXACTLY how strongly acidic or alkaline/basic a solution is • Measured using the PH Scale, which runs from 0 to 14 • Has many different colors, from red for strong acids to dark purple for strong bases. In the middle, neutral pH 7 is indicated by green.

  9. PH Scale • Neutral solutions have a pH of 7 • Acidic solutions have a pH less than 7 • Basic solutions have pH values more than 7 • The closer to pH 0 you go, the more strongly acidic • The closer to pH 14 you go, the more strongly alkaline/basic

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