Controlling the Rate Flashcards
What are the 4 factors that can affect the rate of a reaction?
-Increase in concentration
-Increase in temperature
-Increase in surface area (Decrease in particle size)
-Use of catalyst
What is the rate of a reaction a measure of?
How fast the reactants are being used up and the products are being made
How can the rate be determined?
By measuring changes in the:
-Concentration of reactants or products
-Mass of reactants or products
-Volume of reactants or products
-pH
How is relative rate calculated?
Rate= 1 ÷ Time
How is time calculated in relative rate calculations?
Time= 1 ÷ Rate
What unit is relative rate measured in? (Seconds)
s^-¹
What is the rate of a reaction directly proportional to?
The concentration
What is the rate of a reaction never directly proportional to?
The temperature
What is activation energy (Eª)?
An energy barrier.
The minimum energy required for a reaction to take place.
What is necessary for particles to collide?
-Energy greater to or equal to the activation energy
-The correct collision geometry
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How can changes in pressure affect a reaction?
If the pressure is higher, the chances of a collision are greater
What are potential energy diagrams used for?
To show the energy pathway for a chemical reaction
What is enthalpy change (🔼H)
The energy change that occurs when reactants are converted into products.
What is shown on potential energy diagrams for exothermic reactions?
The energy is released to the surroundings meaning that the products have less energy than the reactants; the enthalpy change is therefore negative.
What is shown on potential energy diagrams for endothermic reactions?
The energy is absorbed from the surroundings meaning that the products have more energy than the reactants; the enthalpy change is therefore positive
