Unit 5
No description yet. This curated deck is ready for daily study.
Card preview (14)
What is an exothermic reaction?
Transfers thermal energy to the surroundings leading to an increase in the temperature of the surroundings
What is an endothermic reaction?
Takes in thermal energy from the surroundings leading to a decrease in the temperature of the surroundings
What is the transfer of thermal energy during a reaction called?
Enthalphy change /\H. It is negative for endothermic reactions - and positive for endothermic reactions
What is activation energy?
The minimum energy that colliding particles must have to react
Bond breaking is a _______ process?
Bond breaking is an endothermic process. The enthalpy change is positive, due to thermal energy being taken IN (absorbed)
Bond making is a _________ process?
Bond making is an exothermic process. The enthalpy change will be negative, due to energy being released
What is the differences between physical change and chemical changes?
Physical changes involve changes in states of matter, while chemical changes produce new substances - involve atomic-level reactions
What is collision theory?
The number of particles per unit volume collide with each other and react only when reactant particles collide with sufficient energy to react. If they have insufficient energy they just bounce off each other
5 Factors affecting rate of reaction:
• Concentration • Pressure • Changing the surface area of solides • Temperature • Catalyst
What does a catalyst do?
Increases the rate of reaction, and is unchanged at the end of the reaction. It decreases the activation energy of a reaction
Practical methods for investigating the rate of reaction:
• Change in mass of a reactant/product • Formation of gas
How are reversible chemical reactions shown?
⇌ with this symbol
A reversible reaction in a closed system is at equilibrium when:
• the rate of the forward reaction is equal to the rate of the reverse reaction • the concentrations of reactants and products are no longer changing