Acids and Bases

Question 1

pH scale

Answer 1

pH 0-3 RED
pH 4-6 ORANGE-YELLOW
pH 7 GREEN
pH 8-10 BLUE
pH 11-14 PURPLE

Question 2

ACID pH scale

Answer 2

0-6

red - yellow

Question 3

NEUTRAL pH scale

Answer 3

7

green

Question 4

BASE

Answer 4

8-14

blue - purple

Question 5

ACIDIC SOLUTIONS

Answer 5

• conduct an electric current
• turn blue litmus paper RED
• sour taste

Question 6

BASIC SOLUTIONS

Answer 6

• conduct an electric current
• turn red litmus paper BLUE
• bitter state
• slippery, soapy feel

Question 7

STRONG ACIDS (3)

Answer 7

• Hydrochloric Acid
• Sulfuric Acid
• Nitric Acid

Question 8

WEAK ACID (6)

Answer 8

• Sulfurous Acid
• Phosphoric Acid
• Hydrofluoric Acid
• Ethanoic Acid
• Carbonic Acid
• Ammonium Salts (Ammonium Chloride/Ammonium Nitrate)

Question 9

STRONG BASE (7)

Answer 9

• Oxides (Li2O, Na2O, K20)
• Magnesium Oxide
• Calcium Oxide
• Barium Oxide
• Lithium Hydroxide
• Sodium Hydroxide
• Potassium Hydroxide

Question 10

WEAK BASE

Answer 10

• Metal Phosphates (Na3PO4, K3PO4)
• Metal Carbonates (Na2CO3, K2CO3)
• Metal Hydrogen Carbonates (NaHCO3, KHCO3)
• Ammonia (NH3, NH3OH)

Question 11

UNIVERSAL INDICATOR

Answer 11

• Is a solution which undergoes several color changes over a wide range of pH’s
• The color is used to “indicate” pH directly
• Universal indicators are usually mixtures of several indicators
• Eg. Litmus Paper

Question 12

METALLIC OXIDES

Answer 12

• Na2O, CaO
• Basic in nature
• Dissolve in water, they DISSOCIATE releasing positive metal ions and oxide ions
• Oxide ion rapidly combines with water to produce OH ions
• When dissolved in water a metal oxide converts into a basic solution of the corresponding metal hydroxide

Question 13

THE ARRHENIUS THEORY

Answer 13

• 1884 described Acid-Base behaviour
• Centered on ability of certain substances that contain H or OH to produce H ions and OH ions when dissolved in H2O
• ACID will IONISE in solution PRODUCING H ions (positive)
• BASE will DISSOCIATE in solution RELEASING OH ions (negative)
• DISADVANTAGES/FAULTS; doesn’t explain/predict acid-base behaviour of other compounds ie. Why salts (don’t contain OH) are basic and not neutral

Question 14

THE BRONSTED LOWRY THEORY

Answer 14

• More comprehensive model of acid-base behaviour
• Gives broader and more satisfactory account of acid-base behaviour
• Able to account for basic properties of NH3, CO32-, S-2 that don’t contain OH
• Shows how these produce OH (pos), OH (neg) in solution by reacting with water in hydrolysis

Question 15

NON METAL OXIDES

Answer 15

• CO2, SO3
• Combine with water to from ACIDS
• Resulting acids then ionic to form H ions and an acidic solution

Question 16

STRONG ACID PROPERTIES

Answer 16

• Produce vigorous reaction in the same conditions
• Undergo complete ionisation
• Will produce higher concentration of H due to complete ionisation