Chem - Quantitative chemistry

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Cards (246)

  • What does the law of conservation of mass state?
    No matter is lost or gained during a chemical reaction.
  • what is a precipitate?
    an insoluble solid
  • Why might the mass of a reaction flask be found to increase?
    One of the reactants is a gas found in the air and all of the products are either solids or liquids.
  • What is an error?
    The difference between a value or quantity obtained in an experiment.
  • What are the 2 types of error?
    random error and systematic error
  • How can random error be affected?
    - The person reading the scale poorly
    - Change in environment, for example, a change in temperature
  • What is systematic errors?
    Errors that occur as a result of a faulty or poorly designed experimental procedure.
  • What is the value of the Avogadro constant?
    6.02 x 10^23 per mole
  • what is a molar mass?

    When one mole of any element is equal to the relative atomic mass of the element in grams.
  • What is the equation for moles?
    Moles = mass ÷ Mr
  • What is meant by concentration?
    The amount of solute there is in a specific volume of the solvent.
  • What is the equation for concentration?
    Concentration = mass ÷ volume
  • What is yield?
    A term used to describe the amount of product you get from a reaction.
  • Why will you never get 100% of yield in a chemical process?
    - some reactants may be left behind in the equipment
    - the reaction may be reversible and a high yield is never possible as the products are continually turning back into the reactants
    - some products are lost during separation and purification stages, such as filtration or distillation.
    - product lost when transferring from one container to another.
  • What is actual yield?

    The recorded amount of product obtained
  • What is theoretical yield?
    The amount of product that would be obtained under perfect practical and chemical conditions
  • How to calculate percentage yield?
    percentage yield = actual yield÷theoretical yield x 100
  • What is atom economy used for?
    To analyse the efficiency of reactions
  • How do you calculate atom economy?
    Atom Economy = Total Mr of the desired product ÷ Total Mr of all the products × 100
  • What factor needs to be considered when choosing a reaction pathway?
    - Atom economy
    - Percentage yield
    - Rate of reaction
    - Equilibrium position
  • What is a reaction pathway?
    The sequence of reactions needed to produce a desired product from a particular set of raw materials.
  • How do you calculate concentration in mol/dm3?
    Moles ÷ Volume
  • How do you go from g dm-3 to mol dm-3?
    Divide by the Molar mass in grams and vice versa.
  • What does Avogadro's Law state?
    At the same condition of temperature and pressure, an equal amount of gasses occupy the same volume of space.
  • What does the molar gas volume at RTP mean?
    The volume occupied by 1 mol of any gas was found to be 24dm^3 or 24,000cm^3.
  • What does RTP stand for?
    Room temperature and pressure
  • How do you calculate volume?
    Volume = Mass × Molar Volume