LESSON 1: Energy Changes in Chemical Reactions

• It is the transfer of energy between two bodies that are at different temperatures.

  Heat (Q)
• It is the energy absorbed or energy released between a system and its surroundings depending on which has a higher temperature.

  Heat flow
• It is a heat flow wherein the system absorbs the heat.

  Endothermic reaction
• It is a heat flow wherein the system releases the heat.

  Exothermic reaction
• What is the symbol used to denote a system that absorbs the heat?

  positive (+Q)
• What is the symbol used to denote a system that releases the heat?

  negative (-Q)
• What is the study of energy changes that occur during chemical reactions and changes of state.

  Thermochemistry
• What is the law of thermodynamics that states that in any chemical or physical process, energy is neither created nor destroyed?

  The Law of Conservation of Energy
• It is also called as the first law of thermodynamics.

  The Law of Conservation of Energy
• It is where the transfer of both matter and energy occurs between the system and surroundings.

  Open System
• This is where only energy can transfer between the system and the surroundings.

  Closed System
• In this system, matter and energy cannot transfer between the system and its surroundings.

  Isolated System
• It is the study of the relationship between heat and other forms of energy, particularly the transfer of heat into work.

  Thermodynamics
• Thermodynamic quantities always consist of these two parts.

  number and sign
• This gives the magnitude of the change in thermodynamics.

  number
• This is indicating the direction of the flow in thermodynamics.

  sign
• It is the energy transferred when an object is moved by a force.

  Work (w)
• It is when the system does the work on the surroundings.

  Expansion (-w)
• It is when the surroundings do the work on the system.

  Compression (+w)
• What is the symbol when it is done on the system?

  positive (+)
• What is the symbol when it is done by the system?

  negative (-)
• What is the symbol when work is done to the system?

  positive (+)
• What is the symbol when work is done to the surroundings?

  negative (-)
• It is the sum of the kinetic energy and potential energy found in a system.

  Internal Energy (E)
• This means that energy was gained from the surroundings.


  +△E
• This means that energy was lost to the surroundings.

  -△E
• It is equal to the amount of heat flow in a system with constant pressure.

  Enthalpy (H)
• TRUE or FALSE

  The heat of a reaction is said to be equal to the enthalpy of the reaction.

  TRUE
• What is the science of measuring heat based on the change in temperature of a physical or chemical change when it absorbs or releases heat?

  Calorimetry
• It is the quantity of heat required to change its temperature by 1 degrees celsius (or 1K).

  Heat capacity
• What is this formula used for solving?$C=$$Q/△T$


  Heat capacity
• $C=$$Q/△T$

  What is Q?

  heat absorbed
• $C=$$Q/△T$

  What is △T?

  change in temperature
• It is the heat capacity per gram of substance.

  Specific heat (c)
• What is the apparatus used to determine the heat flow?

  Calorimeter
• This is a chemical process by which an organic compound reacts with oxygen to form carbon dioxide and water, and release energy in the form of heat.

  Combustion
• This is the amount of heat that is produced in combustion.

  Heat of combustion
• If heat is absorbed in a reaction, it is written as a reactant. If heat is released, it is written as a product.

  Thermochemical equations
• It is the enthalpy change for the chemical equation as it is indicated.

  Heat of reaction
• It is cooler than its surroundings.

  Endothermic