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Acids, Bases & Salts

Acids, Bases & Salts. Introduction. Chemicals may be classed as acids or bases. Things that are neither acids nor bases are neutral . Neutral solution = pure water pH measures how acidic or basic a solution is. Acids.

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Acids, Bases & Salts

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  1. Acids, Bases & Salts

  2. Introduction • Chemicals may be classed as acids or bases. • Things that are neither acids nor bases are neutral. • Neutral solution = pure water • pH measures how acidic or basic a solution is.

  3. Acids • Acid – any compound that produces hydrogen ions in solution (ex: hydrochloric acid, lemon juice, vinegar) • Strong acids can burn skin and eyes and even dissolve metals! • Ex: Hydrochloric acid • HCL  H+ + Cl- • When acids are in water, the H+ molecule breaks loose

  4. Base • Base – hydroxide (OH-) is dissolved in water (Ex: milk, baking soda, drain cleaner) • Strong bases can burn skin & eyes • Bases react more easily with protein than with metal and are often used for cleaning • Ex: Sodium Hydroxide • NaOH Na+ + OH-

  5. Neutralization • Neutralization - Process of reacting an acid and a base to produce a neutral solution • Ex: H+ + OH- HOH (or H2O) • If the quantities of acid and base are right, all the H+ and OH- combine and there will be no excess  then the solution will become neutral

  6. Salts • Salts – compounds produced by the neutralization between an acid and base • Ex: Hydrochloric acid and sodium hydroxide • HCl + NaOH Na+ + Cl- + HOH

  7. How do we determine the difference between and acid and a base??

  8. pH Scale • pH – a unit of measurement that indicates the concentration of hydrogen ions (H+) in a solution • p - stands for potential • H – stands for Hydrogen • pH = the potential of a substance to attaract hydrogen ions • pH Scale goes from 0-14 • 0-6 = Acidic • 7 = Neutral • 8-14 = Basic

  9. x10 x100 pH Scale • Each pH unit is 10 times as large as the previous one • A change of 2 pH units means 100 times more basic or acidic

  10. pH Scale If the solution has a …… 0--------------7---------------14 Acid Neutral Base (*the closer to the end of the scale, the stronger the solution is)

  11. Indicators • Indicators – a substance that changes color when the pH goes above or below a certain value • Types of Indicators – • Litmus paper • Methyl Orange • Phenolphalein • pH Paper • Digital pH meters

  12. The paper is treated with chemicals that change color to show the pH. • When the paper touches the substance being tested, it turns a specific color to tell if the substance is an acid or a base. • How to use pH Paper: • Dip the pH strip into the solution • The pH paper will change color as it reacts to the pH of the solution • Match the color of the strip to the color key on the cover of the container

  13. Why is pH important? Fish can’t live if the pH is too high or too low Soil has to be in a certain pH range for plants to grow and stay healthy.

  14. Why is pH important? Water that has too high or low pH contains harmful dissolved chemicals. Water plant operators keep a careful watch on the pH of our drinking water, to keep it safe.

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