GCSE Chemistry C2
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- Created by: maria bell
- Created on: 30-11-12 22:41
What are bases?
Substances that can react with acids and neutralise them to make a salt and water. hey are usually metal oxides or metal hydroxides. For example, copper oxide and sodium hydroxide.
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What are alkailis?
Bases that dissolve in water.
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What are ions?
charged particles which are formed when atoms, or groups of atoms, lose or gain electrons.
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What are the state symbols?
(s) means solid (l) means liquid (g) means gas (aq) means aqueous
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What is the neuturalisation equation
H+(aq) + OH–(aq) → H2O(l)
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What are the 4 ways of making salts?
acid + metal oxide → salt + water, acid + metal hydroxide → salt + water, acid + metal → salt + hydrogen, acid + metal carbonate → a salt + water + carbon dioxide
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How do you work out the rate of reaction?
amount of reaction used (or product formed) ÷ time taken
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What are the ways to speed up the rate of reaction?
Increase the temperature, Increase the concentration of the reactant, Increase the pressure of the gas, Smaller reactant pieces used, Use a catalyst
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Explain how in terms of particles and their collisions, why increasing the temperature of a reaction changes its rate.
If the temperature is increased: The reactant particles move more quickly More particles have the activation energy or greater The particles collide more often, and more of the collisions result in a reaction The rate of reaction increases.
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Explain how in terms of particles and their collisions, why increasing the concentration in a reaction changes its rate.
If the concentration of a dissolved reactant is increased, or the pressure of a reacting gas is increased, there are more reactant particles in the same volume There is a greater chance of the particles colliding The rate of reaction increases
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Explain how in terms of particles and their collisions, why decreasing the particle size in a reaction changes its rate.
If a solid reactant is broken into small pieces or ground into a powder: Its surface area is increased More particles are exposed to the other reactant There is a greater chance of the particles colliding The rate of reaction increases
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Explain how in terms of particles and their collisions, why adding a catalyst to a reaction changes its rate.
Catalysts increase the rate of reaction without being used up. They do this by lowering the activation energy needed. With a catalyst, more collisions result in a reaction, so the rate of reaction increases.
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What is an isotope?
Atoms of the same element with different numbers of neutrons.
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What is paper chromatography used for?
Paper chromatography is used to analyse coloured substances, such as the coloured pigments in plants and artificial colours used as food additives.
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How does paper chromatography work?
Paper chromatography works because some of the coloured substances are better at dissolving in the liquid than they are at bonding with the paper, so they travel further up the paper.
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What is mass spectroscopy used for?
A mass spectrometer is able to identify substances very quickly and accurately.
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How does mass spectroscopy work?
It can also provide the rfm of the substances separated by gas chromatography. The peak furthest to the right in a mass spectrum is called the 'molecular ion peak'. Its relative mass is the relative formula mass of the substance being analysed.
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What is percentage composition?
Percentage composition is just a way to describe what proportions of the different elements there are in a compound.
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How do you work percentage composition?
(total mass of element present ÷ relative formula mass) x 100
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How do you work out the percentage yield?
percentage yield = (actual mass of product) ÷ (theoretical mass of product) × 100
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Why do we have percentage yield?
1. Reversible reactions may not go to completion 2. Some product may be lost when it is removed from the reaction mixture 3. Some of the reactants may react in an unexpected way.
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How do you work out the Empirical formula?
1. Start with the number of grams of each element, given in the problem. 2. Convert the mass of each element to moles. 3. Divide each mole value by the smallest number of moles calculated. 4. Round to the nearest whole number.
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How do you work out the reacting mass?
Work out the ratio of reactant to product for the required situation. Work out the ratio of reactant to product (or product to reactant) from the masses given. Write them equal to each other
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Other cards in this set
Card 2
Front
What are alkailis?
Back
Bases that dissolve in water.
Card 3
Front
What are ions?
Back
Card 4
Front
What are the state symbols?
Back
Card 5
Front
What is the neuturalisation equation
Back
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