Reactivity 1.1 Flashcards
In terms of kinetic energy, define temperature
The average kinetic energy of the particles
State the units used to measure heat
Joule OR J
During a chemical reaction, state the name of the contents inside the reaction vessel
System
During a chemical reaction, state the name of the contents outside the reaction vessel
Surroundings
Describe the transfer of matter and energy during a chemical reaction in an open system
Both energy and matter can be exchanged with the surroundings
Describe the transfer of matter and energy during a chemical reaction in a closed system
Mass cannot be exchanged with the surroundings, although energy can be exchanged with the surroundings
Describe the transfer of matter and energy during a chemical reaction in an isolated system
Both energy and matter cannot be exchanged with the surroundings
In terms of energy transfer, define an exothermic reaction
Heat energy is transferred from the system to the surroundings during a chemical reaction
In terms of energy transfer, define an endothermic reaction
Heat energy is transferred from the surroundings to the system during a chemical reaction
Describe how the temperature of the surroundings changes during an exothermic chemical reaction
Increases
Describe how the temperature of the surroundings changes during an endothermic chemical reaction
Decreases
State the symbol given to enthalpy
H - must be capital
State the symbol given to enthalpy change
ΔH - must be a capital
State the name of the term that is the total amount of chemical energy in a set amount of a chemical substance
Enthalpy
State the units of measurement for enthalpy
kJ mol⁻
Describe how the temperature of the system changes during an exothermic chemical reaction
Decreases
Describe how the temperature of the system changes during an endothermic chemical reaction
Increases
Describe the enthalpy change during an exothermic reaction
Enthalpy change is negative
Describe the enthalpy change during an endothermic reaction
Enthalpy change is positive
Describe the difference in potential energy between reactants and products during an exothermic reaction
The reactants have higher potential energy than the products
Describe the difference in potential energy between reactants and products during an endothermic reaction
The reactants have lower potential energy than the products
State the name of the label for the y-axis of an energy profile diagram
Potential energy
State the name of the label for the x-axis of an energy profile diagram
Reaction coordinate
In terms of bonds, describe a transition state
A stage of the reaction where all chemical bonds are both partially broken and formed
State the name of the state found at the peak of the energy profile diagram
Transition state
Define activation energy
The minimum energy required for reactants to collide successfully begin to react
Describe how to label the activation energy on an energy profile diagram
Draw an arrow from the potential energy of the reactants to the transition state
State the symbol used to represent activation energy
Ea
Describe how to label the enthalpy change on an energy profile diagram
Draw an arrow from the potential energy of the reactants to the potential energy of the products
State the greek symbol that is used to represent an enthalpy change under standard conditions and states
Theta OR θ
Define the standard enthalpy of reaction
The enthalpy change when the reactants in the stoichiometric equation react to give the products under standard conditions in their standard states
State the standard pressure for an enthalpy change
100 kPa
State the standard concentration for an enthalpy change
1.00 mol dm⁻³
In calorimetry, state the name of the term with the symbol q
Heat transferred
In calorimetry, state the name of the term with the symbol m
Mass of the water or solution
In calorimetry, state the name of the term with the symbol c
Specific heat capacity
Describe how to convert heat transferred (q) to enthalpy (H)
Divide by the amount, in moles, of the substance
In calorimetry, explain why the true maximum temperature may never be reached
The reaction will be losing heat to the surroundings as the reaction begins and moves towards completion
In calorimetry, explain how extrapolation can be used to determine the maximum temperature
Extrapolate the cooling section of the graph until the extrapolated line intersects the time when the reactant was added
In calorimetry, describe the assumption for the rate of cooling
Rate of cooling is constant
In calorimetry, describe TWO assumptions when using a solution
The solution has the same specific heat capacity and density as pure water
State the density of water
1.00 g cm⁻³
Explain why combustion of N₂ is an endothermic reaction
The triple bond in the nitrogen molecule requires a large amount of energy to break, therefore the energy required to break all the bonds is greater than the energy released forming all the new bonds
