Moles , Concentrations , dilutions

• What is the mole used for in chemistry?

  To quantify atoms or molecules in a system
• How many atoms does one mole represent?

  6 × 10²³ atoms
• What is the Avogadro constant?

  6 × 10²³ particles
• How is the Avogadro constant defined?

  Same as atoms in 12 g of 12C
• What unit is used to measure moles?


  mol
• How many atoms are in 1 mol of sodium (Na)?

  6 × 10²³ atoms

  
• Can a mole refer to particles other than atoms?

  Yes, it can refer to ions or molecules
• What is molar mass measured in?

  g mol⁻¹

  
• How does the mass of one mole of carbon compare to hydrogen?

  Carbon is 12 times heavier than hydrogen

  
• What is the mass of one mole of 19F atoms?

  19 g
• What is the mass of one mole of NH₃ molecules?

  17 g
• How many grams are in 0.01 moles of ibuprofen (C₁₃H₁₈O₂)?

  1. 06 g
• What does molar mass allow us to do?

  Compare numbers of atoms or molecules easily

  
• What is the relationship between molar mass and relative atomic mass?

  They have the same value in grams
• How do we calculate the amount of an element in a sample?

  Using mass and molar mass

  
• What is the molar mass of potassium (K)?

  39.1 g mol⁻¹
• How many moles are in 3 g of carbon with a molar mass of 12 g mol⁻¹?

  0.25 mol
• What mass of glucose is needed for 0.8 mol if its molar mass is 180 g mol⁻¹?

  144 g
• What does concentration tell us about a solution?

  Amount of substance per volume

  
• What are the units of molarity?

  mol L⁻¹
• What does a high concentration indicate?

  More substance per unit volume
• How is molarity represented?

  By the symbol M
• How do we calculate the amount of substance in a solution?

  Multiply concentration by volume

  
• How many moles are in 100 mL of a 2 M NaCl solution?

  0.2 mol
• How many moles of HCl are needed for a 1 M solution in 1 L?

  1 mol

  
• What is the mass of 1 mol of HCl?

  36.5 g

  
• What happens to the concentration when a solution is diluted?

  Concentration decreases
• How many moles of HCl are in 10 mL of a 0.5 mol L⁻¹ solution?

  0.05 mol
• What is the concentration of a 500 mL solution with 0.3 mol of glucose?

  0.6 mol L⁻¹
• How do we express the concentration before and after dilution?

  C₁V₁ = C₂V₂

  
• What is the concentration of a diluted HCl solution from 100 mL of a 2 M solution diluted to 1 L?

  0.2 M

  
• How much water is needed to dilute 10 mL of HCl with a concentration of 0.5 mol L⁻¹ to a ten-fold dilution?

  90 mL

  
• What is the concentration of a glucose solution diluted from 8 mL of 0.25 mol L⁻¹ to 0.5 L?

  0.04 mol L⁻¹
• What is a titration used for?

  To determine concentration of unknown solution
• How do titrations measure concentrations?

  By reacting with known concentration solution
• What stoichiometry is used in a 1:1 reaction?

  Equal moles of reactants are needed
• How many moles of Na2CO3 are present if 1.175 × 10⁻² mol of HCl reacted?

  1. 88 × 10⁻³ mol
• How do we calculate the concentration of Na2CO3 solution?

  Using moles and volume relationship

  
• What is molar mass ? 


  Atomic mass of an element
• What is the molar mass of a compound? 


  Add all the atomic masses together