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9 Cards in this Set
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- Back
- 3rd side (hint)
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How do you work out the molar mass/RFM of a substance? Give the units used. |
Add the relative atomic masses of all the elements in the compound together. E.g. CO2 is 12 (C) + 16 (O) + 16 (O) = 44. The units for molar mass are g/mol, RFM has no units. |
The method to work them out is the same. |
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List all the formulas that have moles in. |
1. Moles = Mass divided by RFM 2. Moles = Concentration x volume 3. Moles of gas = volume divided by 24 |
There is 3. |
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What is an empirical formula? |
The simplest whole number ratio of each atom in a compound. E.g. The empirical formula of glucose (C6H12O6) is CH2O |
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How do you calculate the empirical formula of a compound? |
1. Divide the mass/percentage of each element by it's relative atomic mass. 2. Divide all the answers by the smallest answer. 3. Those answers are the mole ratio and tell you how many moles of each element there are.
Example Work out the empirical formula of a compound containing 11.2g of iron and 14.2g of chlorine.
Fe Cl 11.2 divided 14.2 divided by by 56 = 0.2 35.5 = 0.4 0.2 divided 0.4 divided by by 0.2 = 1 0.2 = 2 Mole ratio is 1:2 FeCl2 |
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How do you find out the percentage of an element in a compound? |
% of element in compound = (RFM of element divided by the RFM of the entire compound) x 100 |
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Define concentration. |
The number of moles in a solution per 1dm3. This means that as the concentration increases so does the amount of solute particles in the solution. The units of concentration are mol/dm3. |
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How do you convert volume in cm3 into volume in dm3? |
Divide by 1000. |
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How do you make a 1dm3 of a 1mol/dm3 solution 5 times more dilute? |
If you have 1dm3 of a solution you then times by 5 to find the final volume of the solution which would be 5dm3. The amount of water required to go from 1dm3 to 5dm3 is 4dm3. So you add 4dm3 of water. |
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The reaction below is a neutralisation reaction that can be performed during titrations, complete the reaction
Acid + Alkali = _ _ _ _ + _ _ _ _ _ |
Salt + Water. |
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