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F321 moles

F321 Unit 1 moles

QuestionAnswer
What are isotopes Atoms of the same element that have the same number of PROTONS (atomic) but different number of NEUTRONS (mass)
What is the standard for Relative Mass, to which all other masses of atoms are compared to? Carbon-12
What is the relative Isotopic Mass? the mass of an atom of an isotope, compared with 1/12th of the mass of an atom of Carbon-12
What is the Relative Atomic Mass (Ar)? the mean mass of an atom weighed according to the abundance of the isotopes (and compared with 1/12th of the mass of an atom of Carbon-12)
What is the Relative Molecular Mass? the mean mass of a molecule weighed according to the abundance of the isotopes of each element(and compared with 1/12th of the mass of an atom of Carbon-12)
What is the Relative Formula Mass? The same as the RMM, but applied to giant structure (that do not exist as molecules!)
What is the RAM of Boron, when there is 19.77% of Boron-10, 80.23% of Boron-11? (give to 4sf) 10.80
The RAM of SIlicon is 28.11 a.u. . what does it mean in terms of abundance of isotopes? There is more atoms of isotope-28 than there is of any other isotopes.
What does Avogadro's constant represent? The number of atoms in a mole of Carbon-12
What is the value of Avogadro's number? 6.02x10^23 atoms per mole
What is the Molar Mass? The mass of a mole of a substance.
What is the unit of Molar Mass? g.mol-1
How do you work out the amount of substance in a given mass? moles=mass/Molar Mass
How do you work out the mass of a substance, given the amount? mass=moles x Molar Mass
What is the Empirical Formula? The simplest whole number ratio of atoms of each element present in a compound
What is the Molecular Formula? The number of atoms of each element that make up a molecule
How do you work out the Empirical formula from masses of each element? 1) Divide the mass of each element by the RAM; 2)divide by the smallest number 3) Check that the ratio is whole numbers (so check for .25, .5, .33 or .66)
How do you work out the Molecular Formula from the masses of each element and the RMM? 1)Work out the empirical formula; 2)Work out the mass of the empirical formula; 3)work out the number of units in the molecular formula by dividing RMM by mass-of-empirical-formula; 4) Molecular formula is the number of units x empirical formula
What is Avogadro's Law? equal volumes of gases at the same temperature and pressure contain the same number of moles
What is the molar volume? The volume of a mole of gas. At room temp and atmospheric pressure, molar volume is 24.0dm3.mol-1
How do you work out the amount of gas in a given volume? Number of moles=volume(in dm3 !!!!)/24. Have you remembered to convert cm3 into dm3?
How do you work out the volume of gas, given the number of moles? Volume (in dm3) = Number of moles x 24 Do you need to convert dm3 into cm3?
How do you convert cm3 into dm3? Divide by 1000
How do you convert dm3 into cm3? Multiply by 1000
What is the number of moles in 1080dm3? Moles = 1080 /24 = 45
What is the volume of 0.25moles of Oxygen gas? Volume = 0.25 *24 = 6dm3 Have you remembered the units?
What is the mass of 0.6dm3 of Nitrogen gas (N2)? Moles = 0.6 / 24 = 0.025 Mass = 0.025 x 28 (RMM) = 0.7g Have you remembered the units?
What is the volume of 1.282g of SO2 gas? Moles = 1.282 / 64.1 (RMM) = 0.02 Volume = 0.02 x 24 = 0.48dm3 Have you remembered the units?
What is the mass of 0.500 moles of Fe2O3? RMM of Fe2O3 is 2x55.8+3x16.0=159.6 g.mol-1 Mass = 0.500 x 159.6 = 79.8g Have you remembered the units?
What is the amount of Al2(SO4)3 in 10.269g? RMM of Al2(SO4)3=27.0x2+(32.1+4x16)x3=342.3 g.mol-1 Moles = 10.269 / 342.3 = 0.03 Have you remembered the units?
What is the concentration of a solution? The amount of solute dissolved in 1dm3 of solvent
What is a standard solution? A solution of known concentration
How do you make up a standard solution? 1)weigh out the solute by difference;2)dissolve ina beaker and transfer into flask;3)rinse beaker, funnel and rod into flask;4)top up so that BOTTOM of meniscus is on graduation line
What is a molar solution? A solution with a concentration of 1 mole.dm-3
What is the unit of concentration? mol.dm-3
What is the amount of solution in 24.35cm3 of a 0.125M solution of Potassium Nitrate KNO3? moles = 24.35/1000 x 0.125 = 0.00304 or 3.04x10^-3
What is the concentration of 8.75x10^-3 moles in 50cm3 of solution? Concentration = 8.75x10^-3 / (50/1000)= 0.175 mole.dm-3 Have you remembered to convert cm3 into dm3? Have you remembered the units?
What is the mass concentration of 3.56x10^-3 moles of H2SO4 dissolved in 25cm3 of solution? RMM H2SO4=2x1.0+32.1+4x16.0=98.1 Mass= 3.56x10^-3 x 98.1 = 0.349g Concentration= 0.349 / (25/1000) = 13.96 g.dm-3 Have you remembered the units at each stage?
Created by: UrsulineChem