Chemistry: Patterns of behaviour 8abcdefgand h Flashcards
How can we test to see if a small amount of gas is hydrogen?
Insert a lit splint and hydrogen will give a sqeaky pop!
Rust is the name given to which metal oxide?
Iron oxide
What is iron reacting with when it rusts?
Oxygen, water also become loosely bonded to form hydrated iron oxide.
Why does rust get worse and worse?
It is crumbly and so falls off to expose more iron, which then rusts.
What two condidtions can increase the speed at which iron rusts?
Salty and acidic conditions.
Cars made from aluminium do not corrode, why is this?
Aluminium oxide, which forms of the surface, is a hard, protective layer, very unlike rust.
If aluminium doesn’t rust why aren’t more cars made from it?
It is much more expensive than steel.
Metal + acid —>
salt + hydrogen
metal + oxygen —->
metal oxide
What happens in a displacement reaction?
A more reactive element pushes a less reactive one out of a compound.
Give an example of a displacement reaction involving zinc and copper sulfate.
Zinc + copper sulfate —->Zinc sulfate + copper
Which metal is more reactive, potassium or magnesium?
potassium
Why is lead suitable for roofing, whereas sodium would not be?
Sodium very reactive, would react with rain whereas lead is much less reactive and easily mouldable.
Why does the reactivity of gold and silver make it so useful for jewellery making?
They do not corrode easily and so stay shiny. They also don’t react with moisture on our skin so irritation to skin is less likely.
Most reactive metals are not found naturally. Chemical reactions are necessary to obtain them, why is this?
They exist as compounds within rocks, only the least reactive metals, like gold, are found naturally.
Gold and silver are often used for electrical contacts, why is this?
They are so unreactive that they are safer with electricity passing through them.
If I tested a weak acid with univeral indicatior what colour would I expect to see? What pH is it likely to be?
Yellow/Orange. pH6 to 4.
What is the best thing to use to help remember the colours of univeral indicator.
The colours of a rainbow…with strong acid at the red end and strong alkali and the purple end.
