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CHEMISTRY > Topic 6 > Flashcards

Topic 6 Flashcards

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1
Q

Copper is a valuable

A

Metal

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2
Q

We are running out of high-grade

A

Copper ores

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3
Q

It is expensice to extract copper from

A

Low-grade ores using traditional methods

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4
Q

Scrap iron can be used to produce copper from solutions of copper salts :

A

Iron + copper sulfate -> iron (II) sulfate + copper

Fe(s) + CuSO4(aq) -> FeSO4 (aq) + Cu(s)

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5
Q

As the grade of ores go from High to low the proportion of metal or metal compound goes from

A

High to low

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6
Q

Compared with High-grade ores, low-grade ores:

A

Are more common because most High grade ores have already been used

Are less profitable
Use more energy
Produce more waste when used

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7
Q

What’s phytoextraction

A

A biological method of metal extraction that used plants

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8
Q

What happens in phytoextraction

A

Metal compounds absorbed by roots

Plant concentrates metal compounds in its shoots and leaves

Plants burned

Ash contains metal compounds

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9
Q

What’s bioleaching

A

A biological method of metal extraction that used bacteria.

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10
Q

Copper can be extracted from copper sulfate in the following way

A

The bacteria oxidise sulfide ions S2-
Copper sulfide ores break down
Cu2+ ions are released

The solution that bacteria produce is called a leachate.

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11
Q

What does a leachate contain

A

A high concentration of metal ions

Scrap iron can be used to obtain copper from the leachate

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12
Q

Disadvantages of extracting metals

A

Used up limited resources
Uses a lot of energy
Damages environment

Recycling reduces these disadvantages. Used metal items are collected. Rather than throwing them away. These are taken apart. The metal is melted down to make new items

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13
Q

Recycling metals advantages

A 
Metal ores will last longer 
Less energy is needed 
Fewer quarries and mines are needed 
Less noise and dust are produced
Less land is needed
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14
Q

Drawbacks of recycling

A

Used metal items must be collected and transported to the recycling centre

Different metals must be removed from used items and sorted

Recycling saves different amounts of energy, depending on the metal involved

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15
Q

Recycling metals save energy

A

Different amounts of energy are saved by recycling metals compared with extracting them from ores

Aluminium 94% energy saved
Copper 86% energy saved
Iron and steel 70% energy saved

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16
Q

what’s a LCA

A

Life cycle assessment

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17
Q

Cradle to grave

A

A life cycle assessment of a product is a ‘cradle to grave’ analysis of its impact on the environment

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18
Q

What stages are in a cradle to grave

A

Obtaining raw materials

Manufacturing the product

Using the product

Disposing of the product

19
Q

An LCA is likely to need data on these factors at most or all stages:

A

The use of energy
The release of waste materials
Transport and storage

An LCA is also likely to need data on:
Whether the raw materials needed are renewable or non-renewable
Whether any of the product can be recycled or re used
How the product is disposed of

20
Q

An example of a life cycle eg a car

A 
Obtaining raw materials 
Processing raw materials 
Making car 
Using and making car 
End of useful life 
Disposal
21
Q

Where are transition metals palaced

A

Between group 2 and 3

22
Q

Typical properties of transition metals

A 
High melting point (except mercury, which is in the liquid state at room temperature) 
High density (they have a high mass for thei volume)
23
Q

Are transition metals stronger And harder than the metals in groups 1 and 2

A

Yes so they are often more suitable as construction materials

24
Q

Chemical properties of transition metals

A

Formation of coloured compounds

Catalytic activity

25
Q

Transition metals and their compounds are often useful as

A

Catalysts

26
Q

Catalysts increases the rate of a chemcial reaction without :

A

Altering the products of the reaction
Changing chemically
Changing in mass at the end of the reaction

27
Q

Group 1 and 2 typical properties include

A

Relatively low melting point
Relatively low density
Formation of white or colourless compounds
Lack of catalytic activity

These properties are the opposite of those for transition metals

28
Q

The oxidation of metals results in

A

Corrosion

29
Q

The corrosion of iron and steel is called

A

Rusting

30
Q

Equation for rusting

A

Iron + oxygen + water -> hydrated iron (iii) oxide

31
Q

Rust prevention may rely on keeping oxygen and water away from the surface of the iron or steel rays to do this include

A

Painting
Using oil or grease
Coating with plastic
Coating with another metal

32
Q

Rust prevention may keep oxygen away

A

Store the item in a vacuum container

33
Q

Rust prevention may keep water away

A

Put the item in a container with a desiccant

34
Q

The method of rust prevention you choose depends on

A

Factors such as cost and sustainability
The inside of a food van is protected by a then layer of tin
You would not want to use oil or grease

35
Q

A metal object can be electroplated to:

A

Improve its appearance

Improve its resistance to corrosion

36
Q

Electroplating

A

A thing layer of an unreactive metal such as nickel, silver or gold is deposited on the surface of the metal object, keeping air and water out

37
Q

What is an alloy

A

A mixture of a metal with one or more other elements

These other elements are usually other metals or carbon

38
Q

Pure iron is too soft for most purpose. It is mixed with carbon and other metals to produce alloys called

A

Steels

39
Q

There are many types of steel with different uses depending on their properties. The most common steels are

A

Carbon steels they:
Consist of iron with up to 2% carbon

Are harder and stronger than iron alone

40
Q

What is stainless steel

A

Is an iron alloy that resists corrosion it is used to make cutlery washing machine drums and dishwashers

41
Q

Stainless steel contains chromium :

A

An invisible thin layer of chromium oxide forms on the surface of the steel

It stops air and water reaching the iron

They layer quickly reforms if its scratched

42
Q

Concentration =

A

Amount of solute / volume of solution

43
Q

You can easily convert between mol dm -3 and g/dm 3 using the Mr of the solute :

A

Mol do-3 -> g dm -3 - multiply the concentration by the Mr

G dm-3 -> mol dm-3 - divide the concentration by the Mr

CHEMISTRY (15 decks)

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