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20 Cards in this Set
- Front
- Back
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what is relative atomic mass? |
- average mass of an atom of an element compared to the mass 1/12 of a C-12 atom - is the bigger number on the period table for each element |
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what is relative molecular mass? |
- sum of Ar of elements present in 1 molecule of substance - mass of one molecule of a covalent substance when compared to the mass of 1/12 a C-12 atom |
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what is relative formula mass? |
- mass of one unit of an ionic compound when compared to the mass of 1/12 of a C-12 atom - sum of Ar of elements present in one unit of the ionic compound |
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what is the difference between relative atomic, molecular & formula masses? |
Ar: to find mass of an atom Mr: to find mass of a molecule of a covalent compound relative formula mass: to find mass of a unit of an ionic compound |
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how is percentage by mass of an element in a compound calculated? |
1) multiply the Ar of the element by the no. of atoms of the element 2) divide by the Mr of the compound 3) multiply by 100% |
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what is the mole? |
amount of substance that equals the same no. of particles as 12g of C-12 1 mole = 6.02 X 10^23 |
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how is no. of particles calculated? |
no. of molecules = no. of mol X 6.02 X 10^23 |
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what is molar mass? |
mass of 1 mole unit: g/mol |
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how is molar mass calculated? |
molar mass = no. of moles X Mr |
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what are the characteristics of molar gas volume? |
- equal volumes of all gases at rtp contain the same no. of molecules - molar volume of any gas at rtp/stp = 24dm^3 - unit: mol/dm^3 |
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how is molar volume of gas calculated? |
volume of gas = no. of moles X 24dm^3 |
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what is empirical formula? |
shows elements present and simplest ratio of elements in a compound |
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how is empirical formula calculated? |
1) find mass of compounds 2) find Mr of elements 3) find no. of moles 4) present in simplest mole ratio |
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how is molecular formula calculated from empirical formula? |
empirical formula = AxBy molecular formula = (AxBy)n n = actual Mr of compound / Mr from empirical formula |
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what are the characteristics of concentration of solutions? |
- amount of solute dissolved in a fixed amount of solvent - expressed in terms of mass & no. of moles - g/dm^3 or mol/dm^3 |
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how is concentration in g/dm^3 calculated? |
g/dm^3 = mass / volume |
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how is concentration in mol/dm^3 calculated? |
mol/dm^3 = no. of moles / volume |
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how is concentration converted from g/dm^3 to mol/dm^3? |
g/dm^3 = mol/dm^3 X Mr |
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how is limiting reagent calculated?
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1) calculate no. of moles of both reagents 2) compare mole ratio from balanced equation 3) substitute no. of moles of one reagent limiting reagent = given < needed excess reagent = given > needed |
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how is percentage yield calculated? |
% yield = actual/theoretical X 100 |
