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OCR A-Level Chemistry > Chapter 4 - Acids and Redox > Flashcards

Chapter 4 - Acids and Redox Flashcards

Acids, bases and neutralisation, Acid-base titration and Redox.

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1
Q

What is an acid?

A

When dissolved in water, it will release hydrogen ions as protons into the solution.

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2
Q

What is a strong acid?

A

Releases all of its hydrogen atoms into solution.

It completely dissociates in aqueous solution.

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3
Q

What is a weak acid?

A

Releases a small proportion of its available hydrogen atoms into solution.
It partially dissociates in aqueous solution.

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4
Q

What is a base?

A

A base neutralises an acid to form a salt.

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5
Q

what are some examples of bases?

A

there are several types of bases

metal oxides
metal hydroxides
metal carbonates
alkalis

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6
Q

What is an alkali?

A

A base that dissolves in water releasing hydroxide ions into the solution.

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7
Q

What is the word equation for the neutralisation of acids with metal oxides/hydroxides?

A

Metal oxide/hydroxide + acid -> salt + water

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8
Q

What is the word equation for the neutralisation of acids with alkalis?

A

Acid + alkali -> salt + water

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9
Q

ammonia + acid = ?

A

ammonia ,NH3 reacts with acds by accpeting H+ to form ammonium salts containg an ammonium ion

e,g

HCL + NH3 = NH4Cl

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10
Q

What is the word equation for the neutralisation of acids with carbonates?

A

Carbonate + acid -> salt + water + carbon dioxide

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11
Q

What is a titration?

A

A technique used to accurately measure the volume of one solution that reacts exactly with another solution.

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12
Q

What are titrations used for?

A

titrations are used for Finding the concentration of a solution.
Identification of unknown chemicals.
Finding the purity of a substance.

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13
Q

What are concordant results?

A

Within 0.10 cm^3 of each other.

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14
Q

how to prepare a standard solution? 2 steps for NaOH

A

step 1: find mass of NaOH you want
step2:
weigh NaOH you need
dissolve NaOH, with stirring, in distilled water
pour solution into volumetric flask
rinse beaker with distilled water into the flask
add distilled water to flask - bottom of meniscus on graduation line
place stopper on flask and invert

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15
Q

When can a mean titre be worked out?

A

When two or more concordant results are obtained.

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16
Q

In an acid base titration, what rule is used to determine a solution’s concentration?

A

n(1)=n(2)

c(1)V(1)=c(2)V(2)

17
Q

When is the oxidation number zero?

A

For elements on their own or bonded to atoms of the same element.

18
Q

What is the common oxidation number of oxygen?

A

-2

19
Q

What is the common oxidation number of hydrogen?

A

+1

20
Q

What is the common oxidation number of fluorine?

A

-1

21
Q

What is the common oxidation number of Na+ or K+?

A

+1

22
Q

What is the common oxidation number of Mg2+ or Ca2+?

A

+2

23
Q

What is the common oxidation number of other halides?

A

-1

24
Q

In what special case, can hydrogen have an oxidation number of -1?

A

When in metal hydrides.

i.e. NaH or CaH(2)

25
Q

In what special case, can oxygen have an oxidation number of -1?

A

In peroxides.

i.e. H(2)O(2)

26
Q

In what special case, can oxygen have an oxidation number of +2?

A

When bonded to fluorine.

i.e. F(2)O

27
Q

In ions, what is a trick for determining oxidation numbers?

A

The sum of the oxidation numbers, is equal to the total charge.

28
Q

What do roman numerals mean in the use of iron(II) or iron(III)?

A

Iron(II) represents Fe2+ with oxidation number +2.

Iron(III) represents Fe3+ with oxidation number +3.

29
Q

What is oxidation?

A

The loss of electrons.

30
Q

What is reduction?

A

The gain of electrons.

31
Q

What is oxidation in terms of oxidation number?

A

An increase in oxidation number.

32
Q

What is reduction in terms of oxidation number?

A

A decrease in oxidation number.

33
Q

What is the word equation for the reaction of a metal with acid?

A

Metal + acid -> salt + hydrogen

OCR A-Level Chemistry (34 decks)

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