c3 quantitative chemistry

• What is actual yield in a chemical reaction?

  The amount of product actually produced
• How is atom economy defined?

  Measure of starting materials as useful products
• What does the Avogadro constant represent?

  Number of atoms in a mole of substance
• What does Avogadro's law state?

  Equal moles of gases occupy same volume
• How is concentration defined in chemistry?

  Amount of substance in a certain volume
• What does the conservation of mass state?

  No atoms are lost or made in reactions
• What is a limiting reactant?

  The reactant completely used up in a reaction
• What is the unit for measuring chemical amounts?

  The mole, symbol mol
• What does percentage yield compare?

  Actual yield to theoretical yield of product
• What is theoretical yield?

  Maximum product amount from given reactants
• What is thermal decomposition?

  Reaction when heat breaks down a compound
• How is relative formula mass (Mr) calculated?

  Sum of relative atomic masses in formula
• What must be true in a balanced chemical equation regarding Mr?

  Sum of Mr of reactants equals products
• What is the formula for percentage yield?

  Percentage yield = Amount of product produced x 100
• What does yield refer to in a chemical reaction?

  Yield refers to the amount of product obtained
• How do you calculate the moles of a reactant?

  Use mol. = mass / molar mass
• How do you calculate the theoretical mass of a product?

  Use mass = mol. x molar mass
• What does atom economy measure?

  It measures useful products from starting materials
• Why is high atom economy important?

  For sustainable development and economic reasons
• What is the formula for calculating atom economy?

  =(Mr of desired product / sum of Mr of all reactants) x 100
• How can you find the mass number of an element?

  By looking in the top left corner of its nuclear symbol
• What does the mass number represent?

  Number of protons plus neutrons in the nucleus
• What is relative atomic mass denoted by?

  ar
• How do you find the relative formula mass of a compound?

  Add together the relative atomic masses of all atoms
• What is the process to find the relative formula mass of a compound?

  1. Identify the molecular formula.
  2. Find the relative atomic masses of each element.
  3. Add the relative atomic masses of all atoms in the formula.
• What is the formula for calculating percentage mass of an element in a compound?

  • Percentage mass = (ar of element × number of atoms) / mr of compound × 100
• Relative Atomic Mass (Ar) is the average mass of all the isotopes of that element
• Relative Formula Mass (Mr) is found by adding together the relative atomic masses of all the atoms in that compounds formula
• Mass number = Ar (relative atomic mass) the mass number is on top atomic number on bottom
• Calc % mass of particular element in a compound:

  $\frac{Mass\ No\ (Ar)\ ofelement\ \times\ No\ ofatoms\ of\ that\ element}{Mr\ of\ compound\ }\times100$
• What does the term "mole" refer to in chemistry?

  A unit to measure the amount of substance
• How many particles are in one mole of a substance?

  6.02 times 10 to the 23 particles
• What is Avogadro's constant?

  6.02 times 10 to the 23 particles
• How do you calculate the number of moles in a sample?

  Mass divided by relative formula mass
• How do you find the mass of a substance from moles?

  Multiply moles by relative formula mass
• What does a chemical equation represent in terms of moles?

  Ratios of reactants and products in moles
• What is the relationship between moles and mass in chemistry?

  • Moles are calculated as mass divided by relative formula mass.
  • Mass can be found by multiplying moles by relative formula mass.
• What are the steps to calculate the mass of an element in a compound?

  1. Determine the number of moles of the compound.
  2. Multiply by the relative atomic mass of the element.
  3. Subtract from the total mass to find the mass of other elements.
• How do we verify the conservation of mass using relative formula masses?

  By comparing total masses on both sides of the equation
• Why might the mass appear to change in a reaction involving a gas?

  Gas can escape into the air during the reaction