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PROPERTIES OF ACIDS & BASES

PROPERTIES OF ACIDS & BASES . WEEK OUTLINE: . Monday: Properties of Acids & Bases Tuesday: Acid Precipitation Wednesday: Properties of Acids & Bases Lab Stations Thursday: Neutralization Reactions Friday: Acid/Base Quiz Making an Indicator – Acids & Bases at Home Lab . NEXT WEEK: .

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PROPERTIES OF ACIDS & BASES

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  1. PROPERTIES OF ACIDS & BASES

  2. WEEK OUTLINE: • Monday: Properties of Acids & Bases • Tuesday: Acid Precipitation • Wednesday: Properties of Acids & Bases Lab Stations • Thursday: Neutralization Reactions • Friday: Acid/Base Quiz • Making an Indicator – Acids & Bases at Home Lab

  3. NEXT WEEK: • Monday (Dec 14): Review Class • Tuesday (Dec 15): Chemistry Test • Wednesday- Friday (Dec 16-18) Start Climate Change Unit

  4. WHAT DO YOU THINK? • Page 265: True or False? • Stomach acid can dissolve metals like a coin in a child’s stomach? • We all contribute to the production of acid precipitation? • Even diet soda drinks can cause tooth decay? • Medications for heartburn work by cooling the stomach? • All acids are dangerous? • Soft drinks can be used to make spilled drain cleaner safer?

  5. PROPERTIES OF ACIDS AND BASES • Young children like to explore by putting things in their mouths • Occasionally objects get swallowed! • Coins are the most common object to be swallowed • Once in the stomach, the coin in bathed in a corrosive mixture that includes hydrochloric acid (HCl (aq)) and other digestive juices • The concentration of HCl in your stomach is about the same as ones we have used in class - what do you think happens to the coin?

  6. PROPERTIES OF ACIDS • Chemists classify substances by their properties • Acids - are substances that react with metals and carbonates, conduct electricity, turns blue litmus red, and neutralize bases • Acids also taste sour, but you should never taste chemicals in a lab! • Very useful in food industry - act as preservatives (vinegar and lemon juice)

  7. PROPERTIES OF ACIDS • Reaction with Metals • Acids react with metals to produce hydrogen gas • Ex. hydrochloric acid + zinc → hydrogen gas + zinc chloride • 2HCl (aq) + Zn (s) → H2 (g) + ZnCl2 (aq)

  8. PROPERTIES OF ACIDS • Reaction with Carbonates • Acids react with carbonates to produce carbon dioxide gas • Ex. acetic acid + sodium hydrogen carbonate → carbon dioxide + water + sodium acetate • HC2H3O2 (aq) + NaHCO3 (aq) → CO2 (g) + H2O (l) + NaC2H3O2 (aq)

  9. PROPERTIES OF ACIDS • Electrical Conductivity • Many acids are good conductors of electricity • A solution can only conduct electricity if it contains ions • Since acids are molecular compounds they do not contain ions

  10. PROPERTIES OF ACIDS • Electrical Conductivity (Continued) • However, collisions with water molecules break acid molecules apart to form cations (hydrogen ions) and anions • Ex. Hydrochloric acid forms hydrogen and chloride ions: • HCl (aq) → H+ (aq) + Cl- (aq)

  11. CHEMICAL FORMULAS OF ACIDS • All acids produce hydrogen ions when dissolved in water • Hydrogen ions give acids their properties • The chemical formula of an acid begins with an H and is usually followed by an “(aq)” • This is because an acid shows its properties when dissolved in water • Hydrogen chloride - gas that would dissolve in water in lungs when inhaled = forming highly corrosive hydrochloric acid

  12. NAMES OF ACIDS • Two common groups of acids: • Binary Acids (Table 1 Page 269)

  13. NAMES OF ACIDS • Oxyacids – related to polyatomic ions (Table 2 Page 269)

  14. PROPERTIES OF BASES • Bases -conduct electricity, change the colour of acid-base indicators, feel slippery and taste bitter

  15. PROPERTIES OF BASES • Electrical Conductivity • Bases are electrolytes, meaning their solutions are good conductors of electricity • Ex. NaOH (sodium hydroxide) is an electrolyte because in water it separates into ions as it dissolves • NaOH (s) → Na+ (aq) + OH- (aq) • Many common bases are ionic compounds - they are made up of ions (unlike acids) • As they dissolve in water, their ions are released

  16. NAMES AND CHEMICAL FORMULAS OF BASES • Table 4 Page 271

  17. COLOUR WITH ACID-BASE INDICATORS • A substance that changes colour depending on the acidity or basicity of the solution is known as an acid-base indicator

  18. COLOURS OF COMMON SYNTHETIC ACID-BASE INDICATORS • Table 3 Page 270

  19. THE PH SCALE • pH scale - a numerical scale of all the possible values of pH from 0 to 14 • pH is a measure of how acidic or basic a solution is • A solution with a pH of 7 is considered neutral • A solution with pH of less than 7 is considered acidic • A solution with pH of greater than 7 is considered basic

  20. THE PH SCALE CONTINUED • Solutions with highest hydrogen ion concentration are near zero on pH scale • Solutions with highest concentrations of hydroxide ions are near 14 on pH scale • Can use the words “acidity” or “basicity” to describe the properties of acids or bases

  21. ACID AND BASE HOMEWORK • Page 271 #1-5

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