SC14- quantitive analysis

• What is the term used to describe the amount of product obtained from a chemical reaction?

  Yield
• How can yield be measured in chemistry?

  In grams or moles
• What does the term 'actual yield' refer to?

  The amount of product actually obtained from a reaction
• What does 'theoretical yield' mean?

  The yield expected based on calculations
• If 2 grams of hydrogen reacts with 16 grams of oxygen, what is the theoretical yield of water?

  18 grams
• Why might the actual yield be less than the theoretical yield?

  There are several reasons, including incomplete reactions, side reactions, and product loss
• What is one reason why reactants might not fully react?

  The reaction could be slow or reversible
• What happens in a reversible reaction like the formation of ammonia?

  Some products can break down back into reactants
• What are side reactions?

  Reactions that produce different products than expected
• In the nitrogen and oxygen reaction, what unexpected product might form?

  Nitrogen dioxide
• What is one way product loss can occur during a reaction?

  Gaseous products can escape
• Why might liquid or solid products be lost during filtration?

  Some liquid may remain in the beaker or on the filter paper
• How do you calculate percentage yield?

  Actual yield divided by theoretical yield, multiplied by 100
• If the actual yield is 15 grams and the theoretical yield is 18 grams, what is the percentage yield?

  83.3%
• What does a percentage yield of 100% indicate?

  All predicted products were obtained
• What does a percentage yield of 0% indicate?

  No product was obtained from the reaction
• What are the common reasons for a lower actual yield compared to theoretical yield?

  • Reactants may not fully react
  • Side reactions producing unexpected products
  • Loss of product during the process
• How do you calculate the percentage yield from a chemical reaction?

  1. Take the actual yield
  2. Divide by the theoretical yield
  3. Multiply by 100 to get a percentage
• What is the main aim of the chemical reaction discussed in the study material?

  To make hydrogen
• What is the significance of the other product in the reaction, such as carbon dioxide?

  It is considered waste
• What is the term used to describe the percentage of reactants that form useful products?

  Atom economy
• How do you calculate atom economy?

  Divide the relative formula mass of the desired product by the total relative formula masses of all reactants, then multiply by 100
• What is the relative formula mass (mr) of hydrogen?

  2
• What is the relative formula mass (mr) of carbon monoxide?

  28
• What is the relative formula mass (mr) of water?

  18
• What is the total relative formula mass of the reactants in the reaction?

  46
• What is the atom economy of the reaction producing hydrogen from carbon monoxide and water?

  1. 35%
• Why is an atom economy of 4.35% considered low?

  Because it means that only 4.35% of the reactants are converted into the useful product
• What is the atom economy of the reaction producing ammonia from nitrogen and hydrogen?

  100%
• Why is it important to consider atom economy in chemical processes?

  • Raw materials are expensive
  • Less sustainable to use large quantities for small amounts of products
  • Waste products can be costly to dispose of and harmful to the environment
• What are the best solutions to improve atom economy?

  • Use a more efficient reaction
  • Find a use for waste products as useful by-products
• What other factors should be considered when evaluating the profitability of a reaction?

  • Percentage yield
  • Cost of raw materials
  • Position of equilibrium
  • Rate of reaction
  • Cost of maintaining conditions (temperature and pressure)
• What should you be able to determine by the end of the video?

  The concentration of an acid or alkali in moles per decimeter cubed and in grams per decimeter cubed
• What is the purpose of the titration calculation discussed in the video?

  To calculate the concentration of an acid or alkali from the reacting volumes and the known concentration of one solution
• How do you convert volumes to decimeters cubed?

  By dividing the volume in centimeters cubed by 1000
• What is the volume of hydrochloric acid required to neutralize sodium hydroxide in the sample question?

  17 centimeters cubed
• What is the concentration of sodium hydroxide in the sample question?

  0.1 moles per decimeter cubed
• How do you calculate the number of moles of sodium hydroxide?

  By multiplying the concentration by the volume
• What is the number of moles of sodium hydroxide in the sample question?

  0.0025 moles
• What does the absence of large numbers in front of the acid or alkali indicate?

  That one mole of hydrochloric acid reacts with one mole of sodium hydroxide