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22 Cards in this Set
- Front
- Back
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How do you identify the limiting reagent? |
Determine the number of moles of each reactant and compare it to the molar ratio in the chemical equation h |
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How do you calculate moles? |
n= m/M |
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How do you calculate number of atoms? |
Number of moles x Avogadro constant |
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What is the Avogadro constant equal to? |
6.02 x 10^23 |
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How do you calculate per cent composition? |
Mass of x in 1 mole of a compound/ molar mass of compound x 100/1% |
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What are the 5 steps for working out the empirical formula? |
1. Identify all the elements present in the sample 2. Determine the mass if each element by assuming 100g and placing into a ratio 3. Change grams to moles and divide by its molar mass 4. Determine the whole number ratio by dividing all numbers of moles by the smallest number of moles. Write a ratio 5. If necessary use a multiplication factor to achieve whole numbers |
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How do you find the molecular formula of a compound? |
1. State unknowns 2. Calculate molar mass of the empirical formula 3. Find the multiple of the empirical formula by dividing the molar mass of the compound by the molar mass of empirical formula 4. Times empirical formula by the multiple of it |
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How do you find the molar ratio of a compound? |
1. Write a balanced equation 2. The coefficients for the reaction indicate the relative number of moles of each molecule that is needed |
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How do you find the relative abundance of an isotope? |
Label the smaller mass isotope x and label the larger one 1-x |
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When attempting a stoichiometric question, what is the first action needed to be taken? |
Balance the equation |
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What are the 1st, 2nd, 3rd and 4th ionisation energies of Al? |
1. 557.54 2. 1816 3. 2744 4. 11577 |
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What are the 1st, 2nd, 3rd and 4th ionisation energies of Ga?` |
1. 578 2. 1979 3. 2964 4. 6101 |
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What are the 1st, 2nd, 3rd and 4th ionisation energies of Be |
1. 899 2. 1757 3. 14848 4. 21006 |
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When writing out the electron configuration for an element once up to 3d how is it written? |
4s is after 3d |
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What is the electron configuration for Chromium? |
[Ar] 3d^5 4s^1 |
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What is the electron configuration for Copper? |
[Ar] 3d^10 4s^1 |
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As you move down a group, the elctronegativity.... |
decreases |
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As you move across a period, electronegativity... |
increases |
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Why does electronegativity increase moving left to right? |
Positively charged ions are more attracted to the negatively charged ions |
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For example if given the following question, how would you work it out? If 120g of propane (C3H8) is burnt in excess oxygen, calculate the mass of water produced. |
1. Make a ratio of reactants and products 2. Find number of moles for propane 3. Write the ratio of propane to water and times oxygen to get the number of H2O produced 4. Find mass of Oxygen |
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How do you calculate percentage yield? |
experimental/theoretical x 100% |
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If given a balanced equation how do you calculate the moles of one compound given 1 mole of another compound? |
1. Find the multiple needed to give one mole of that substance 2. Multiply that multiple by the compound moles needed to be found |
