chem calcs

• What is used to compare quantities of substances in quantitative chemistry?

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

  Add the relative atomic masses of elements
• What does the conservation of mass state in a chemical reaction?

  Total mass of reactants equals products
• What is the relative formula mass of MgCl₂?

  95
• How do you calculate the percentage mass of an element in a compound?

  Percentage mass = (Ar x number of atoms / Mr) x 100
• What does one mole of any substance contain?

  An Avogadro number of particles
• What is the Avogadro constant?

  1. 02 x 10²³
• What is the formula to calculate the number of moles?

  No. of moles = mass / Mr
• What is the role of limiting reactants in a chemical reaction?

  They determine the maximum amount of product
• How many moles of oxygen are needed for one mole of methane?

  Two moles
• What happens when a substance is dissolved in water?

  It dissociates into its ions
• What is the formula for calculating concentration?

  Concentration = moles / volume
• What does percentage yield indicate in a reaction?

  Mass of product made compared to theoretical mass
• How is percentage yield calculated?

  % yield = (total mass of products / total mass of reactants) x 100
• What does atom economy measure in a reaction?

  Efficiency of producing desired product from reactants
• What is the formula for calculating atom economy?

  Atom economy = (RAM of desired product / total RAM of reactants) x 100
• What volume does one mole of any gas occupy at RTP?

  24 dm³
• What does RTP stand for in gas volume measurement?

  Room temperature and pressure