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SC13H
Pearson GCSE Chemistry
| Question | Answer |
|---|---|
| If a metal is described as ductile what does that mean? | It can be stretched out to make a thin wire |
| If a metal is described as malleable what does that mean? | It can be hammered into a different shape without shattering. |
| What is a catalyst? | A substance that speeds up a process, without itself being used up. |
| State the two meanings of the word oxidise | To gain oxygen in a chemical reaction, or to lose electrons. |
| What is rusting and what two substances must be present for it to occur? | The corrosion of iron or steel. (Water and oxygen must be present for rusting to occur.) |
| Explain the meaning of sacrificial protection. | Using a more reactive metal to protect iron from rusting |
| Write a half equation for the oxidation of Magnesium. | Mg(s) --> Mg2+ (aq) + 2e- |
| What is electroplating? | Using electricity to coat one metal with a thin layer of another metal. |
| Write the half equations for the electroplating of copper by silver. (State at which electrode each reaction occurs) | At the silver anode Ag(s) -->Ag+ (aq) + e- At the copper cathode Ag+(aq) + e- -->Ag(s) |
| Why is coating steel cans in tin not an example of sacrificial protection? | Because tin is less reactive than iron |
| What is an alloy? | A metal with one or more other elements (usually metals) added to improve its properties. |
| Explain why alloys are often stronger than pure metals. | Different sized atoms distort the metal structure and make it difficult for layers of atoms to slide over each other. |
| What is an alloy? | A mixture of two or more elements, at least one of which is a metal |
| Give a reason for alloying a metal | To make it harder, to make it less reactive |
| Explain why alloys can be harder than pure metals | Different size of atoms disturb the layers to stop them sliding over each other |
| What are the typical properties of transition metals? | High melting point, high density, form coloured compounds, act as catalysts for particular reactions. |
| How can rusting of iron be prevented? | By excluding water and oxygen |
| What can you exclude to reduce rusting of iron. | water and oxygen |
| How else can rusting of iron be prevented? | By sacrificial protection |
| What is sacrificial protection? | Coating the metal in a more reactive metal that will react in preference to the one you are trying to protect |
| What is electroplating? | Using electrolysis to coat the metal to be protected in a thin layer of another metal |
| Why is electroplating used? | It improves appearance and increases resistance to corrosion. |
| Why is iron alloyed to make steel | to improve resistance to corrosion and increase strength. |
| How does alloying gold increase its strength | The different sized atoms mixed with the gold atoms disrupt the layers of identical gold atoms and stop them rolling over one another. |
| What properties of gold make it suitable for its uses | unreactive - jewellry lasts well |
| What is copper used for? Explain your answers. | wires - because it is a good conductor, water pipes - because it is unreactive |
| What causes corrosion of metals? | oxidation |
| What is aluminium used for? | Drinks cans - lightweight, ladders - low density |
| What is brass used for? | Door fittings - unreactive, attractive |
| What is magnalium used for? | Scientific instruments - increased malleable,lower density than aluminium |
| What is another name for oxidation of metals? | corrosion |
| What are irons properties? | High melting point, high density, form coloured compounds, act as catalysts for particular reactions. |
Created by:
Davenant Foundation School
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