C3

• What does the law of conservation of mass state?

  No atoms are lost or made
• What is the relationship between the mass of products and reactants?

  Mass of products equals mass of reactants
• What does Mr represent in chemistry?

  Relative formula mass of a chemical
• In an open system, how can mass change during an experiment?

  Gas can be added or escape
• What happens to mass if a reactant is a gas?

  Mass increases during the reaction
• What happens to mass if a product is a gas?

  Mass decreases during the reaction
• What is a chemical formula?

  Represents chemicals with symbols and numbers
• What is an atom?

  The smallest particle of an element
• What is a mole in chemistry?

  Represents 6.02 x 10²³ particles
• What is a limiting reactant?

  The reactant completely used up in a reaction
• What does excess mean in a chemical reaction?

  More of a chemical than needed
• How is the mean calculated?

  Add numbers and divide by count
• What is range in a set of numbers?

  Highest minus lowest number
• What does uncertainty measure?

  How close numbers are to the mean
• How is a chemical formula structured?

  Starts with capital letters, numbers indicate quantity
• What does a number after brackets in a chemical formula indicate?

  How many of that group are present
• What is the relative formula mass (Mr)?

  Mass of one mole of a chemical in grams
• How do you find the number of moles?

  Using the equation: moles = mass / Mr
• What is concentration in solutions?

  Mass of solute in 1 dm³ of solution
• How does adding more solute affect concentration?

  Increases the concentration of the solution
• How do you convert cm³ to dm³?

  Divide by 1000
• What is the concentration of a solution with 2 g of HCl in 400 cm³ of H₂O?

  5 g/dm³
• How can uncertainty in measurements be calculated?

  Range divided by 2
• What is the result of the mean and uncertainty calculation?

  Mean ± uncertainty
• What do balancing numbers in a chemical equation indicate?

  The ratio of moles of each chemical
• How can mole ratios be used in chemical reactions?

  To find moles of one chemical from another
• How do you find the balanced chemical equation from masses?

  Use mass to find mole ratio
• What is the balanced equation for magnesium carbonate decomposing?

  MgCO₃ → MgO + CO₂
• How do you calculate the mass of magnesium oxide produced?

  Mass = moles x Mr
• What is the Mr of magnesium oxide?

  40 g
• How do you find the mass of chlorine gas needed for sodium chloride production?

  Use mole ratios from the balanced equation
• What is the mass of chlorine gas needed when 69 g of sodium is reacted?

  142 g