Gases, solutions , concentrations

• What is the volume occupied by one mole of any gas at 20 °C and 1 atm?


  24 dm³
• At what conditions does one mole of any gas occupy the same volume?


  At room temperature (20 °C) and 1 atm pressure
• How do you calculate the volume of a known mass of gas at r.t.p.?


  Volume of gas = $\frac{Mass \ of \ gas}{M. \ of \ gas} \times 24$
• What is the volume of 319.5 g of chlorine at r.t.p.?


  108 dm³
• How can you find the volume of one gas in a reaction if you know the volume of another gas?

  By using the stoichiometry of the balanced equation
• How much carbon dioxide is formed when 30 dm³ of oxygen reacts with carbon monoxide?


  60 dm³ of CO₂
• What is concentration in chemistry?


  • Measure of how crowded substances are in a solution
  • Amount of substance in a certain volume of solution
• What is the formula to calculate concentration in g/dm³?


  Concentration = $\frac{mass \ of \ solute}{volume \ of \ solvent}$
• How do you calculate the mass of a solute in solution?


  mass = concentration × volume
• What is the concentration in g/dm³ of a solution with 30 g of sodium chloride in 0.2 dm³ of water?


  150 g/dm³
• What is the concentration in mol/dm³ of a solution with 2 moles of salt in 500 cm³ of water?


  4 mol/dm³
• How do titrations help in calculating concentrations?


  • They determine volumes needed for two solutions to react completely
  • Use known concentration and volumes to find the unknown concentration
• What is the formula for calculating concentration in mol/dm³?


  Concentration = $\frac{number \ of \ moles \ of \ solute}{volume \ of \ solvent}$
• How do you find the number of moles of a known substance in a titration?

  Using the formula no. of moles = concentration × volume
• How many moles of sulfuric acid are present if 0.00250 moles of NaOH react with it?


  0.00125 moles of H₂SO₄
• What is the concentration of sulfuric acid if 0.00125 moles are present in 30.0 cm³?

  0.0417 mol/dm³
• How do you convert concentration from mol/dm³ to g/dm³?

  1. Find concentration in mol/dm³
  2. Use mass = moles × Mr to convert to g/dm³
• What is the relative formula mass of sulfuric acid (H₂SO₄)?

  98
• What is the concentration in g/dm³ of the sulfuric acid solution if the moles are 0.041666...?

  1. 08 g/dm³
• What should you remember about measurements in titration experiments?

  • All measurements have some uncertainty
  • Titrations are often repeated for accuracy
  • Average of repeated measurements is calculated
• What is the formula for calculating the concentration of a solution in grams per dm³?


  Concentration = mass / volume
• How is concentration expressed in grams per dm³?


  It is calculated as grams of solute per 1000 cm³ of solution
• If 40g of NaOH is dissolved in 2.5 dm³ of water, what is the concentration?


  16 g/dm³
• What is the concentration of 24g of copper sulfate in 480 cm³ of water?


  50 g/dm³
• How do you convert cm³ to dm³ in concentration calculations?


  By dividing the volume in cm³ by 1000
• What is the formula for calculating the volume of gas in m³?


  Volume of gas = moles x 24
• If you have 3.5 mol of Cl₂, what is the volume of the gas?


  84 m³
• How many moles are in 60 dm³ of O₂?


  1. 5 mol
• If you have 27g of water vapor, how many moles do you have?


  1. 5 mol
• What is the molar mass of water used in the calculation of moles from grams?


  18 g/mol
• How do you find the volume of a product when given the volume of a reactant in a gas reaction?


  Use the stoichiometric ratios from the balanced equation
• In the reaction N₂ + 3H₂ → 2 NH₃, what volume of ammonia is produced from 15 dm³ of nitrogen with excess hydrogen?


  36 cm³
• What is the ratio of nitrogen to ammonia in the reaction N₂ + 3H₂ → 2 NH₃?


  1. 2
• Under what conditions do gas volume calculations apply?


  At room temperature and pressure
• What are the steps to calculate the concentration of a solution?

  • Measure the mass of solute in grams
  • Measure the volume of solution in dm³
  • Use the formula: Concentration = mass / volume
• What are the key concepts in gas volume calculations?


  • Volume of gas = moles x 24
  • Stoichiometric ratios from balanced equations
  • Conditions: room temperature and pressure