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33 Cards in this Set
- Front
- Back
- 3rd side (hint)
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Relative atomic mass from isotopic abundance |
Multiply each relative isotopic mass by its % isotopic abundance Add up results Divide by 100 |
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Use mass spectra to work out relative atomic mass |
Multiply each isotopic mass by its isotopic abundance Add up results Divide by sum of the isotopic abundance |
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Avogadro constant |
Number of particles in one mole 6.02x10^23 |
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Finding the number of moles from the number atoms or molecules |
Number of particles you have Divided by Number of particles in a mole |
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Find the number of moles using Mr |
Mass of substance Divided by Molar mass |
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Molar gas volume |
Volume in dm3 Divided by Molar gas volume Equals number of moles |
At r.t.p it is 24 |
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Ideal gas equation |
pV=nRT Let’s you find the number of moles in a certain volume at any temperature and pressure |
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Gas constant |
8.134 JK-1mol-1 |
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Empirical formula |
Smallest whole number ration of atoms in a compound |
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Molecular formula |
The actual number of atoms of each type of element in a molecule |
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Ionic equations show reacting particles |
Nitric acid with sodium hydroxide HNO3+NAOH=NaNO3+ H2O Ionic substances will dissolve, braking u the ions. (H+)+(NO3-) +(Na+) +OH-=(Na+) +(NO3-)+H2O Cross out ions that appear on both sides. Ionic equation is H+OH=H2O Make sure the charges balance |
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Actual yield |
Actual mass of product Always less then theoretical yield |
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Percentage yield |
Actual yield/theoretical yield x100 Tells how wasteful the process is. But not how wasteful the reaction is. |
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Atom economy |
Measure of the proportion of reactant atoms that become the desired product Molecular mass of desired product/ sum of molecular masses of ALL products X100 |
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Ionic structure |
Ionic compounds conduct electricity when molten or dissolved. Not when they are solid Have high melting and boiling points held together by strong electrostatic forced. Takes a lot of energy to break them. Tend to dissolve in water |
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Covalent bonding |
A covalent bond is the strong electrostatic attraction between a shared pair of electrons and the nuclei of the bonded atoms. |
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Strength of a covalent bond |
Shown by its Average Bond Enthalpy Measures energy required to break a covalent bond. |
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Dative covalent bonding |
Where both electrons come from one atom |
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Balance equations show reaction stoichiometry |
Calculate the mass of iron oxide produced if 28g of iron is burnt in the air. 2Fe+3/2O2=Fe2O3 Molar mass of Fe is 55.8g mol-1 Number of moles in 28g is 28/55.8=0.50 moles 2 moles of age produces 1 mole of Fe2O3 0.50 moles of Fe produced 0.25 moles of Fe2O3 Molar mass of Fe2O3 is 159.6g mol-1 Mass of Fe2O3 is 0.25*159.6= 40g |
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Reaction stoichiometry |
Tells the ratio of reactants to products |
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Stat |
How much gas is produced when 15g of sodium is reacted with excess water at rtp 2Na+2H2O=2NaOH+H2 M of Na is 23.0g mol-1 In 15g 15/23.0 =0.65 moles 2 moles of Na produces 1mole of H2 Volume of H2 is 0.325*24=7.8dm3 |
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Acids |
Means all of the chemical will react |
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State symbols |
S=solid L=liquid G=gas Aq=aqueous (solution in water) |
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The |
Proton donors Release H ions Common acids: HCl, H2SO4, HNO3, CH3COOH |
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Bases |
Proton acceptors Grab H ions Bases that are Soluble in water known as alkalis They release OH- ions Common bases: NaOH, KOH and NH3 |
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Find moles from concentration |
Concentration*volume (cm) Divide by 1000 |
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Theoretical yield |
The maximum product you can get If no chemical are lost Mass of reactants and number of moles |
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How to measure liquid |
Always read the volume from the bottom of the meniscus when it is at eyelevel. |
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How to measure gases? |
Gases can be measured with a gas syringe. They should be measured at room temperature pressure as the volume of a gas changes with temperature and pressure. Make sure it’s completely sealed and that the plunger move smoothly. |
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How to measure solid? |
You weigh solids using a balance. Make sure that your balance is set to exactly 0 before weighing your substance. If you need to transfer the solid to another container make sure that it’s all transferred or you could reweigh the Weighing container after you transferred the solid so that you can work out exactly how much you’ve added to your experiment. |
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Precise results are repeatable meaning that if the same person does the experiment again is in the same methods and equipment they will get the same results. They also need to be reproducible meaning that if someone else does experiment with a different method or piece of equipment results will still be the same. |
Precise results are repeatable meaning that if the same person does the experiment again is in the same methods and equipment they will get the same results. They also need to be reproducible meaning that if someone else does experiment with a different method or piece of equipment results will still be the same. |
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How to minimise any errors that might sneak into your data? |
Use apparatus and techniques correctly. Take measurements correctly. And repeat your experiments and calculate the mean |
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Percentage error |
To calculate percentage error
Uncertainty divided by reading times by 100.
E.g. the balance measures to the nearest 0.2 g and is used to measure the change in mass of a substance. But initial mass is measured as 40.4 g. The final mass is measured at 22.0 g calculate the percentage error? 40.4 takeaway 22.0 equals 18.4 g – the change in mass. The balance measures to the nearest 0.2 g so each reading has an uncertainty of 0.1 g to readings have been combined so the total uncertainty is 0.1×2 which equals 0.2 g so the change in mass percentage error is 0.2 divided18.4×100 = 1 .1% |
For any piece of equipment you use, that uncertainty will be half the smallest increments they equipment to measure in either direction. If combining measurements you will need to combine their uncertainties |
