#50-53

• What is Le Chatelier's principle about?

  It describes how the position of equilibrium in a reversible reaction is affected by changes in temperature, pressure, and concentration.
• What does the position of equilibrium refer to?

  It refers to the ratio of reactant particles to product particles when a reaction is at equilibrium.
• How do we describe the position of equilibrium if there are more reactants than products?

  We say that the equilibrium lies to the left.
• How do we describe the position of equilibrium if there are more products than reactants?


  We say that the equilibrium lies to the right.
• What happens to the position of equilibrium when conditions of a reversible reaction change?

  The position of equilibrium shifts to counteract the change.
• In the production of ammonia from nitrogen and hydrogen, what is the overall energy change of the forward reaction?

  • 92 kilojoules per mole
• What does a negative energy change indicate about the forward reaction?

  It indicates that the forward reaction is exothermic, releasing energy to the surroundings.
• What type of reaction is the backward reaction if the forward reaction is exothermic?

  The backward reaction must be endothermic.
• If the temperature of the system is decreased, in which direction will the equilibrium shift?

  The equilibrium will shift to the right, favoring the exothermic direction to release heat energy.
• If the temperature of the system is increased, in which direction will the equilibrium shift?

  The equilibrium will shift to the left, favoring the endothermic direction.
• How does an increase in pressure affect the position of equilibrium?

  The equilibrium will shift to the side with fewer molecules to reduce pressure.
• In the ammonia production reaction, which side has fewer molecules?

  The right side has fewer molecules, with only two molecules of ammonia.
• If the pressure is decreased, in which direction will the equilibrium shift?

  The equilibrium will shift to the left, favoring the side with more molecules.
• What happens to the equilibrium if more nitrogen is added to the sealed container?

  The equilibrium will shift to the right, forming more ammonia.
• What are the factors that affect the position of equilibrium according to Le Chatelier's principle?

  • Temperature
  • Pressure
  • Concentration
• What is the relationship between the direction of equilibrium shift and the type of reaction (exothermic or endothermic)?

  • Decreasing temperature shifts equilibrium towards the exothermic direction.
  • Increasing temperature shifts equilibrium towards the endothermic direction.
  • Increasing pressure shifts equilibrium towards the side with fewer molecules.
  • Decreasing pressure shifts equilibrium towards the side with more molecules.
• What area of chemistry focuses on compounds that contain carbon?

  Organic chemistry
• Why is carbon considered a useful element for making large compounds?

  Because each atom of carbon can form four strong bonds
• What are hydrocarbons defined as?

  Compounds formed from carbon and hydrogen only
• What is the name of the hydrocarbon with the formula C4H10?

  Butane
• Why is butanol not considered a hydrocarbon?

  Because it contains an oxygen atom
• What is the simplest type of hydrocarbons called?

  Alkanes
• What is the molecular formula for methane?


  C1H4
• What is the molecular formula for ethane?

  C2H6
• What is the molecular formula for propane?

  C3H8
• What is the molecular formula for butane?

  C4H10
• How do the number of carbon and hydrogen atoms change in alkanes?

  They grow by one carbon and two hydrogens each time
• What is a homologous series in organic chemistry?

  • A group of organic compounds with similar properties
  • React in a similar way
  • Can be described by a general formula
• What is the general formula for alkanes?

  CnH2n+2
• If an alkane has three carbon atoms, how many hydrogen atoms does it have?

  Eight hydrogen atoms
• What is the molecular formula for octane, which has eight carbon atoms?

  C8H18
• What does it mean for alkanes to be saturated compounds?


  Every carbon atom has four single covalent bonds
• What happens to the structure of propane if one of its single bonds is changed to a double bond?

  It would no longer be classified as an alkane
• What will be covered in the next video after discussing alkanes?

  • Properties of alkanes
  • Writing equations for their combustion
• What are alkanes classified as in terms of their chemical structure?


  Alkanes are a homologous series of hydrocarbons.
• What elements do alkanes contain?


  Alkanes contain only carbon and hydrogen atoms.
• What is a key characteristic of alkanes regarding double bonds?

  Alkanes have no double bonds.
• What are the names of the first four alkanes in the series?

  • Methane (C1H4)
  • Ethane (C2H6)
  • Propane (C3H8)
  • Butane (C4H10)
• How does the boiling point of alkanes change with the length of the carbon chain?

  The boiling point increases with chain length.
• What state do the first four alkanes exist in at room temperature?

  The first four alkanes exist as gases at room temperature.