Unit 7 - Acids, bases and salts Flashcards

1
Q

Properties of acids

A
  • Contain H^+ ions
  • Soluble in water
  • Sour to the taste
  • Corrosive
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2
Q

Properties of bases

A
  • Found as metal oxides (O^2-), metal carbonates (CO3^2-), metal hydroxides (OH^-) or ammonia
  • Some are soluble in water - called alkalis and are metal hydroxides
  • Soapy to the touch
  • Corrosive
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3
Q

Indicator

A

A chemical substance that changes color with changing H^+ concentration

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4
Q

Types of indicators

A
  • Litmus
  • Methyl orange
  • Universal indicator paper
  • Thymolphthalein
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5
Q

Litmus colors for acids and bases

A
  • Acid = Red
  • Base = Blue
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6
Q

Methyl orange colors for acids and bases

A
  • Acid = Red
  • Base = Yellow
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7
Q

Universal indicator paper colors for acids and bases

A
  • Strong acid = Red
  • Weak acid = Orange/Yellow
  • Strong base = Purple
  • Weak base = Blue
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8
Q

Thymolphthalein colors for acids and bases

A
  • Acid = colorless
  • Base = Blue
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9
Q

pH scale values

A
  • 0-6 = Acid
  • 7 = Neutral
  • 8-14 = Alkaline (base)
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10
Q

Equation for an acid and metal reacting together

A

Acid + Metal –> Salt + Hydrogen

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11
Q

Equation for an acid and base reacting together

A

Acid + Base –> Salt + Water

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12
Q

Equation for an acid and metal carbonate reacting together

A

Acid + Metal carbonate –> Salt + Carbon dioxide + Water

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13
Q

Equation for an acid and ammonia reacting together

A

Acid + Ammonia –> Salt

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14
Q

Products of ammonium salts reacting with metal hydroxides

A
  • Ammonia
  • Salt
  • Water
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15
Q

Brønsted-Lowry theory of acids and bases

A
  • Acid is capable of donating a proton
  • Base accepts a proton
  • Water is amphoteric - can act as both acid and base
  • Strong acids and bases ionize completely in water
  • Weak acids and bases only partially ionize in water
  • The conjugate base of an acid is formed after the acid donates the proton
  • The conjugate acid of a base is formed after the base accepts a proton
  • The two species in a conjugate acid-base pair have the same molecular formula except the acid has an extra proton compared to the conjugate base
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16
Q

Elements that make acidic oxides

A

Non-metals

17
Q

Elements that make basic oxides

A

Metals

18
Q

Amphoteric

A

A substance that behaves both as an acid or a base

19
Q

Examples of amphoteric oxides

A
  • Aluminum oxide
  • Zinc oxide
20
Q

Possible reactants that amphoteric oxides can react with

A
  • Acid and bases to form a salt and water
21
Q

Salts

A

Ionic compounds made of positive ions/cations and negative ions/anions

22
Q

Sources of cations

A
  • Metal
  • Metal oxide
  • Metal hydroxide
  • Metal carbonate
23
Q

Sources of anions

A
  • Hydrochloric acid (Cl^-)
  • Sulfuric acid (SO4^2-)
  • Nitric acid (NO3^-)
24
Q

Salt in a solid state

A

Crystals

25
Q

Hydrated salt

A

When water molecules get inside the crystal structure and chemically bond to the metal ion - known as water of crystallization

26
Q

Anhydrous salt

A

When crystals exist with no water molecules bonded into the crystal structure

27
Q

Representation for water of crystallization

A

Dot between the salt and water to show they have been reacted together

28
Q

Method for getting a salt from an acid and base reaction

A
  1. Place a known volume of acid using a volumetric pipette into a conical flask
  2. Add a few drops of the indicator
  3. Add the alkali to the acid until the indicator changes color
  4. Record the volume of alkali added to the acid
  5. Repeat without the indicator or add decolonizing charcoal (will have to be heated and filtered)
  6. Transfer to an evaporating dish and heat to evaporate off some of the water until crystals form
  7. Leave to cool
  8. Filter to get the crystals
  9. Dry the crystals on filter paper
29
Q

Soluble salts

A
  • All ammonium, sodium and potassium salts
  • All nitrate salts
  • Nearly all chloride, bromide and iodine salts
  • Nearly all sulfates
  • Ammonium, sodium and potassium carbonates salts
  • Ammonium, sodium and potassium hydroxide salts
30
Q

Insoluble salts

A
  • Silver chloride, solver bromide, solver iodide and lead chloride
  • Barium sulfate, calcium sulfate and lead sulfate
  • Most carbonates
  • Most hydroxides
31
Q

Products when two solutions containing soluble salts mix

A
  • One salt forms an insoluble solid/precipitate and the solution becomes cloudy
  • The other product is a soluble salt that stays in the solution
32
Q

Method of preparing an insoluble salt

A

1.Mix equal quantities of the two soluble salts
2. Filter to remove the insoluble salt or precipitate
3. Wash the precipitate with water
4. Leave to dry