SC8 Flashcards

1
Q

How do you know when a solution is neutral?

A

Solutions with a pH of 7

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2
Q

How do you know when a solution is acidic?

A

When they have a pH of less than 7

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3
Q

How do you know when a solution is alkaline?

A

When they have a pH greater than 7

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4
Q

How do you find the pH of a solution?

A

Use universal indicator

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5
Q

When are polyatomic ions formed?

A

They’re formed when small groups of atoms, held together by covalent bonds, lose or gain electrons

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6
Q

What do acids produce when they’re dissolved in water?

A

Excess of hydrogen ions

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7
Q

What do alkaline produce when dissolved in water?

A

Excess of hydroxide ions

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8
Q

The higher the number of hydrogen ions in a certain volume…

A

The higher the concentration
Higher concentration=more acidic
Lower pH

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9
Q

The higher the concentration of hydroxide ions…

A

More alkaline the solution

Higher pH

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10
Q

What is the concentration like in neutral solutions?

A

Contain low, equal concentrations of hydrogen and hydroxide ions

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11
Q

What happens to the pH if the concentration of hydrogen ions is increased by a factor of 10?

A

pH decreases by 1

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12
Q

What happens to the pH if the concentration of hydrogen ions is decreased by a factor of 10?

A

pH increases by 1

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13
Q

What are strong acids?

A

Their molecules dissociate into ions when dissolved in water and produce high concentration of hydrogen ions

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14
Q

What are weak acids?

A

Don’t dissociate completely into ions when dissolved in water

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15
Q

What are bases?

A

They are substances that neutralise acids to form salt and water

All metal oxides are bases

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16
Q

What happens during neutralisation?

A

Hydrogen ions combine with oxide ions to form water

Removes hydrogen ions so pH increases

17
Q

How are salts produced during neutralisation?

A

Replacing hydrogen ions with metal ions

18
Q

How do you make sure the prepared salt is pure?

A

Filtered to remove residue from filtrate leaving salt and water
Then allowed to evaporate to crystallise
If water evaporates slowly= bigger crystals

19
Q

Which type of bases are soluble (dissolve in water)

A

Alkali bases

20
Q

Where are the hydroxide bases found?

A

Group 1 and 2

21
Q

Why is the formula for group 2 hydroxides MOH(2)

A

Ions formed by group 2 have 2+ charge but hydroxide ions have 1- charge
Brackets show that 2 OH ions are needed to produce a neutral compound

22
Q

How do you obtain a neutral solution?

A

Mix together acid and alkali in right proportions so solution contains water and desired salt

23
Q

What is the burette’s role during titration?

A

Used to add acid to fixed volume of alkaline in a conical flask

Controlled using tap at bottom

24
Q

What is the role of the pipette in titration?

A

More accurate and repeatable way of measuring out alkali for conical flask

Few drops of indicator added to alkali to follow reaction

25
Q

When is the end point in titration?

A

Indicator changes colour

Indicator used are methyl orange or phenolphthalein

26
Q

How do you make pure dry salts from titration

A

Carry out titration
Note exact volume of acid needed to neutralise alkaline
Use burette to add correct volume of acid (without indicator)
Evaporate water from solution formed

27
Q

How do metals such as copper and silver react with dilute acids?

A

Not at all

28
Q

How do metals such as potassium and sodium react with dilute acids?

A

React explosively

29
Q

How do metals such as magnesium and zinc react with dilute acids?

A

React steadily as in the middle of reactivity series

30
Q

What is effervescence?

A

When hydrogen gas bubbles are produced

Reaction also produces salt

31
Q

What are spectator ions?

A

Ions that don’t change during reaction

32
Q

What happens when a metal reacts with a carbonate?

A

Produces salt, water and carbonate

33
Q

What harkens during the reaction with a metal and carbonate?

A

Hydrogen ions from acid react with the carbonate ions to form water and carbonate dioxide molecules

34
Q

How do you test for carbon dioxide?

A

Bubble gas through limewater

If carbon dioxide present, limewater turns milky

35
Q

What is a precipitation reaction?

A

Where soluble substances in solutions cause an insoluble precipitate to form

36
Q

Which substances are soluble in water?

A

Sodium, potassium and ammonium salts, carbonate & hydroxides
All nitrates
Most chlorides and sulfates

37
Q

Which substances are insoluble in water?

A

Silver, lead chlorides
Lead, barium,calcium sulfates
Most carbonates and hydroxides

38
Q

How do you predict whether a precipitate forms?

A

Precipitate will form if both of the products aren’t soluble

Only form if insoluble

39
Q

How do you prepare insoluble salts?

A

Mix 2 solutions in beaker and then filter mixture
Pour a little bit of distilled water through funnel
Remove filter paper containing precipitate and dry