Acids, Bases and Oxides Flashcards

1
Q

Define

Acids

A

An acid is a substances that dissociates when dissolved in water to produce hydrogen ions as the only positive ions

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2
Q

Define

Basicity

A

The number of hydrogen atoms in an acid which are replacable by a metal

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3
Q

What are monobasic, dibasic and tribasic acids?

Own Definiton

A

Monobasic: one molecule, one H+ ion
Dibasic: one molecule, two H+ ions
Tribasic: one molecule, three H+ ions

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4
Q

What are strong and weak acids?

A

Strong acid: Substance that dissociates completely when dissolved in water to produce a high concentration of hydrogen ions

Weak acid: Substance that partially dissociates in water to form low concentrations of hydrogen ions

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5
Q

Can acids and alkalis conduct electricity?

A

Yes, they have mobile ions

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6
Q

What are the different reactions that can take place with an acid?

A
  1. Acid+reactive metal –> Salt+hydrogen
    (Effervescence of a colourless gas is seen)
  2. Acid+metal carbonates –> carbon dioxide gas+salt+water
    (effervescence of a colourless gas is evolved which forms a white precipitate with limewater)
  3. Acid+bases–> salt+water
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7
Q

What are methods to identify gases?

A
  1. Lighted splint (hydrogen) –> positive result; extinguishes with a ‘pop’ sound
  2. Limewater (carbon dioxide) –> positive result; white precipitate is formed
  3. Litmus paper (carbon dioxide or ammonia)
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8
Q

Define

Bases

A

Bases are metal oxides or metal hydroxides that react with acids to form salts. Bases that are soluble in water are called alkalis

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9
Q

Define

Alkalis

A

An alkali is a soluble base, which dissociates when dissolved in water to produce hydroxide ions

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10
Q

What are weak and strong alkalis?

A

Weak alkalis: A substance that partially dissociates when dissolved in water to produce a low concentration of hydroxide ions

Strong alkalis: A substance that completely dissociates when dissolved in water to produce a high concentration of hydroxide ions

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11
Q

What are the different reactions that can take place with a base?

A
  1. Acids+bases –> salt+water
  2. Ammonium salts+alkalis–> ammonia gas+water+salt
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12
Q

What are acidic oxides?

A

When oxygen reacts with non-metals, they form acidic oxides. React with water to form acids.
Acidic oxides can react with alkalis even when insoluble

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13
Q

What are basic oxides?

A

Basic oxides are formed when oxygen reacts with metals. Ionic compounds. Can react with acids in neutralisation reactions

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14
Q

What are amphoteric oxides?

A

Metallic oxides that can react with both acids and bases to form salt and water. Oxygen that reacts with zinc, aluminium or lead (ZAP)

ZAP hydroxides also amphoteric in nature

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15
Q

What are neutral oxides?

A

When oxygen reacts with non-metals they form neutral oxides. Insoluble in water. These are mainly monoxides

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16
Q

When do we use the different indicators?

A
  1. Methyl orange/ screened methyl orange: For acidic substances lower than pH 5
  2. Thymolphthalein: For alkali substances greater than pH 9
  3. Litmus paper: For extreme ends of alkalis and acids
  4. Universal indicator: General purpose, but usually avoided as too many colours
17
Q

What are the names given to the two liquids used in titrations?

A

In the beaker: Analyte
In the burette: Titrant

18
Q

Where is the end point in titrations?

A

In the middle of the steep climb/drop of pH

19
Q

What is the pH of the salt produced in titrations?

A

The same pH as the end-point

20
Q

What do we have to consider in application questions for the use of acids and bases?

A

Possible reactions that may occur after the use of these chemicals with pre-existing chemicals

21
Q

How do you find the pH of a substance by calculation?

A

pH= -lg(H+)

Where H+ is the concentration of hydrogen ions in mol/dm3 of the solution