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Chemical Calculations

Kate Blowers 8 questions 5.0 (1 rating)

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Questions in this quiz (8)

  1. 1What is the correct equation for working out the percentage mass of an element in a compound?
    1. A(Relative formula mass x number of atoms of that element)/relative atomic mass of compound
    2. B(Relative atomic mass x number of atoms of that element)/relative formula mass of compound
    3. C(Relative atomic mass x relative formula mass of compoun)/number of atoms of that element
  2. 2A mole is a system chemists use to count huge quantities of [blank_start]atoms or molecules[blank_end]. It is given the symbol [blank_start]n[blank_end], and is measured in a unit called the mole, shorthand [blank_start]mol[blank_end]. A mole of any substance contains the same number of atoms that are contained in [blank_start]12[blank_end]g of the isotope [blank_start]carbon-12[blank_end]. One mole of a substance is simply the [blank_start]relative atomic mass[blank_end] or [blank_start]formula mass[blank_end] expressed in [blank_start]grams.[blank_end]
    1. Aatoms or molecules
    2. Bn
    3. Cmol
    4. D12
    5. Ecarbon-12
    6. Frelative atomic mass
    7. Gformula mass
    8. Hgrams.
  3. 3The reactant that gets used up first in a reaction is called the limiting reactant
    1. ATrue
    2. BFalse
  4. 4Which of these do you need to work out the limiting reactant?
    1. AA balanced symbol equation
    2. BThe relative formula mass
    3. CThe number of moles of each reactant
    4. DThe number of electrons
  5. 5Percentage yield is the amount of a produce you [blank_start]actually make[blank_end] as a [blank_start]percentage of the amount[blank_end] you should [blank_start]theoretically make.[blank_end]
    1. Aactually make
    2. Bpercentage of the amount
    3. Ctheoretically make
  6. 6Why does a high percentage yield matter to people in the industry?
    1. AIf a yield is know for a particular product you can work out how much reactant is needed
    2. BA higher percentage yield = less product to produce more = higher profit
    3. CIt's easier to work out information
    4. DRaw materials are scarce and expensive and so must be carefully conserved
  7. 7What is the correction equation for working out percentage yield?
    1. APercentage yield = (Theoretical yield/actual yield) x 100
    2. BPercentage yield = (Number of atoms/theoretical yield) x 100
    3. CPercentage yield = (Actual yield/theoretical yield) x 100
  8. 8Very few reactants have a percentage yield of 100% because:
    1. AProducts may be left behind in the apparatus
    2. BIt violates the law of conservation of mass
    3. CThe reaction may not have completely finished
    4. DThe raw minerals may not be pure
    5. EThe atoms are destroyed in the reaction
    6. FSome reactants may give unexpected products

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Description
A summary of the chemical calculation topics - in particular with regards to moles
Language
English
Views
147
Rating
5.0 out of 5 · 1 rating
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