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Chemistry- year 8 > Acids and alkalis > Flashcards

Acids and alkalis Flashcards

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1
Q

What is an acid?

A

A substance with a pH lower than 7 that dissolves some metals and has a sour taste

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2
Q

What is a base?

A

a substance with a pH above 7 that has a bitter taste

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3
Q

What is an alkali?

A

a soluble base that effervesces acids

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4
Q

What does neutral mean?

A

a substance with a pH of 7

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5
Q

What is a solvent?

A

a liquid that dissolves a solute

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6
Q

What is a solute?

A

a substance that dissolves in a solvent

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7
Q

What does aqueous mean?

A

a substance that has water as its solvent

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8
Q

What does dilute mean?

A

A solution that contains little dissolved solute

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9
Q

What does concentrated mean?

A

A solution that contains a lot of dissolved solute

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10
Q

What is a chemical indicator?

A

An indicator that changes colour to identify a solution’s pH

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11
Q

What is neutralisation?

A

A chemical reaction between an acid and a base, that makes a chemical neutral (pH7) producing salt and water

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12
Q

List the chemical indicators:

A

-universal indicator
-litmus paper
-phenolphthalein
-methyl red/orange
-bromothymol blue
-cresol red
-red cabbage indicator

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13
Q

What is the pH scale range?

A

1-14

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14
Q

What is the range of a strong acid

A

1-3 (red)

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15
Q

What is the range of a weak acid

A

4-6 (orange/yellow)

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16
Q

What is a neutral substance’s pH?

A

pH 7 (green)

17
Q

What is the range of a weak alkali?

A

8-10 (light/dark blue)

18
Q

What is the range of a strong alkali?

A

11-14 (purple)

19
Q

What happens to litmus paper in an acid, an alkali or a neutral substance?

A

in an acid, blue litmus paper turns red and red litmus paper stays red.
in an alkali, blue litmus paper stays blue and red litmus paper turns blue
a neutral substance has no effect on litmus paper, so blue litmus paper stays blue and red litmus paper stays red

20
Q

What is the word equation for neutralisation?

A

Base + acid → salt + water (pH 7)

21
Q

How can we tell if something is an alkali? (by the substance’s name)

A

anything that has ‘hydroxide’ in it is an alkali

22
Q

Give the formulas and pH of these substances:

Sulfuric acid
Hydrochloric acid
Nitric acid
Hydrofluoric acid
Ethanoic acid
Sodium chloride (salt)
Ammonium hydroxide
Calcium hydroxide
Potassium hydroxide

A

H2SO4 (pH1)
HCl (pH2)
HNO3 (pH3)
HF (pH3)
CH3COOH (pH4)
NaCl (pH7)
NH4OH (pH8-10)
Ca(OH)2 (pH9-11.5)
KOH (pH12.5)

23
Q

What colour is the colour of ethanoic acid in universal indicator, what is its pH number, and is it an acid, an alkali or a neutral substance?

A

it’s orange in universal indicator, it has a pH of 4, and it is a weak acid

24
Q

What colour is the colour of distilled water in universal indicator, what is its pH number, and is it an acid, an alkali or a neutral substance?

A

it’s green in universal indicator, it has a pH of 7, and it is a neutral substance

25
Q

What colour is the colour of lime water in universal indicator, what is its pH number, and is it an acid, an alkali or a neutral substance?

A

it’s blue in universal indicator, it has a pH of 10/11, and it’s a moderate alkali

26
Q

What colour is the colour of sulphuric acid in universal indicator, what is its pH number, and is it an acid, an alkali or a neutral substance?

A

it’s red in universal indicator, it has a pH of 1/2, and it is a strong acid

27
Q

What colour is the colour of sodium carbonate in universal indicator, what is its pH number, and is it an acid, an alkali or a neutral substance?

A

it’s blue in universal indicator, it has a pH of 10/11, and it is a moderate alkali

28
Q

What colour is the colour of salt water (sodium chloride solution) in universal indicator, what is its pH number, and is it an acid, an alkali or a neutral substance?

A

it’s green in universal indicator, it has a pH of 7, and it is a neutral substance

29
Q

What colour is the colour of dilute hydrochloric acid in universal indicator, what is its pH number, and is it an acid, an alkali or a neutral substance?

A

it’s red in universal indicator, it has a pH of 1/2, and it is a strong acid

30
Q

What colour is the colour of dilute sodium hydroxide in universal indicator, what is its pH number, and is it an acid, an alkali or a neutral substance?

A

it’s purple in universal indicator, it has a pH of 13/14, and it is a strong alkali

31
Q

What colour is the colour of nitric acid in universal indicator, what is its pH number, and is it an acid, an alkali or a neutral substance?

A

it’s red in universal indicator, it has a pH of 1/2, and it is a strong acid

32
Q

What colour is the colour of dilute ammonia solution in universal indicator, what is its pH number, and is it an acid, an alkali or a neutral substance?

A

it’s blue in universal indicator, it has a pH of 10/11, and it is a moderately strong alkali

33
Q

What are some common acids found in a chemistry lab?

A

-Hydrochloric acid – HCl
-Sulphuric acid - H2SO4
-Nitric acid - HNO3

34
Q

What are some common alkali found in a chemistry lab?

A

-potassium hydroxide - KOH
-calcium hydroxide - Ca(OH)2
-Sodium Hydroxide –NaOH

35
Q

What is methyl red’s colour in an acid and alkali?

A

it is red in an acid and yellow in an alkali

36
Q

What is methyl orange’s colour in an acid and alkali?

A

it is red in an acid and yellow in an alkali

37
Q

What is phenolphthalein’s colour in an acid and alkali?

A

it is colourless in an acid and pink in an alkali

38
Q

What is bromothymol blue’s colour in an acid and alkali?

A

it is yellow in an acid and blue in an alkali

39
Q

What is cresol red’s colour in an acid and alkali?

A

it is yellow in acid and purple in alkali

Chemistry- year 8 (6 decks)

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