Rate & Extent Of Chemical Change Flashcards
How can rate of reaction be calculated?
Rate of Reaction = Amount of reactant used / Time
Rate of Reaction = Amount of product used / Time
How can be the quantity of reactant / product be measured?
Measured in grams / volume in cm3 / measured in moles (mol/s)
How do you find the rate of reaction graphically?
Draw tangents to curves and use the tangent of the curve
Calculate the gradient of a tangent to the curve on these graphs as a measure of rate of reaction at specific time
What are the factors that affect the rate of reaction?
Concentration Pressure Surface area Temperature Catalysts
What is collision theory?
Chemical reactions can occur only when reacting particles collide with each other and with sufficient energy
What is activation energy?
The minimum amount of energy that particles must have to react
State the outcome if the concentration of a solution, the pressure of reacting gases & the surface area of a solid increases.
Increases the frequency of collisions and so increases the rate of reaction
How do the collisions of the particles change when the temperature is increased?
Increasing the temperature increases the frequency of the collisions and makes the collisions more energetic.
This means the rate of reaction increases
What are catalysts?
Substances that speed up chemical reactions without being changed or used up in the reaction
What do enzymes act as in biological systems?
Catalysts
Are catalysts included in the equation of a reaction?
No
How do catalysts affect the activation energy in a reaction?
Decrease the activation energy
This increases the proportion of particles with energy to react
What do catalysts provide?
A different pathway for a chemical reaction that has a lower activation energy
What are reversible reactions and give an example.
In some chemical reactions, the products of the reaction can react to produce the original reactants
The direction of the reaction can be changed by changing the conditions
(e.g. for forwards reaction use hot conditions and for reverse use cool)
E.g. The Haber Process: hydrogen + nitrogen ⇌ ammonia
If a reaction is endothermic one way, what energy change will be in the opposite direction?
How much energy is transferred each way?
If a reversible reaction is endothermic one way, it is exothermic in the opposite direction.
The same amount of energy is transferred each way (just for one the energy will be lost and for the other the same amount will be gained)
