Physical And Chemical Changes In Our Modern Society Flashcards Preview

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Flashcards in Physical And Chemical Changes In Our Modern Society Deck (12):
1

Why shouldn't we use magnesium for jewellery and what is magnesium used for?

We would not use magnesium for jewellery because it would readily react with hot water when taking a shower or doing the dishes! However, it's chemical properties did have a use by photographers. Photographers used to burn powdered magnesium to provide enough white light to take a photograph. Cameras now have built-in electronic flashes.

2

Why is copper best used for and why?

Copper is used for electrical wires because it is malleable, ductile and the best conductor of electricity. Coppers reactivity is also poor and so it will not react with many of the substances in our environment.

3

What does copper react with and disadvantages.

It does react with oxygen. Copper shines for a while after being polished but eventually turns a darker, duller colour. This is due to a reaction between the copper atoms in the metal and oxygen in the air.

4

Why is copper a very popular metal for making domes on buildings?

Copper reacts with air or sea water over a long period of time. The green patina that is produced due to this chemical reaction is verdigris. You may have seen it on copper comes on some of your buildings.

5

What can the incandescent light bulb do?

The incandescent light bulb produces light by passing an electric current through a very thin wire. When the current passes through the filament, it heats up.

6

What happens the thinner the wire in a incandescent light bulb?

The thinner the wire, the hotter it gets. The filament gets so hot it glows giving off light. One reason tungsten metal is chosen as the filament is its very high melting point.

7

The benefits and disadvantages of the thinner wire.

This means that it can withstand the very high temperatures without melting. However, the temperatures get very high, tungsten and actually react with oxygen and ignite. This is the reason that the incandescent light bulb is filled with a noble gas such as argon.

8

Why are incandescent light bulbs cheap to purchase?

They are nowhere as near as energy efficient as compact, fluorescent lamps. So your electricity bill would be more expensive in the long run if you used incandescent light bulbs.

9

What of the world's supply are rapidly decreasing?

The world's supply of crude oil are rapidly decreasing. Oil companies are being forced to look for new supplies further offshore and in deeper waters. Existing technologies and materials are not designed to function at these distances,depths and pressures. Carbon steel pipes will only last six months and stainless steel pipes only two years under such conditions before replacement.

10

What is used to fix the problem for oil companies?

Material chemists have invented carbon polymer chains that survive at temperatures more than -60*.

11

What do corrosion pipe liners do?

Corrosion-resistant pipe liners assist with the flow of hydrocarbons through the pipe.

12

One example of physical and chemical properties will affect how and where it is used.

We use gold, silver and platinum for jewellery because there are lustrous and mallets and have relatively high melting points. They are also relatively unreactive, so that they will not react with water or the acids in our skin.