6-The Rate And Extent Of Chemical Change Flashcards
(22 cards)
What is the rate of reaction
How fast the reactants change into products
What is an example of a slow rate of reaction
Chemical weathering
What is an example of a fast rate of reaction
Explosions are very fast and release a lot of gas
What does the rate of a chemical reaction depend on
The collision frequency,
Energy transferred during collision- need enough energy to be successful
What 4 things increase rate of reaction
Temperature,
Surface area,
Concentration of solution or pressure of gas,
Presence of a catalyst
Why does increasing temperature increase the rate of reaction
Particles gain more energy and move faster, this means they collide more frequently.
Also more energy from temperature means that more collisions will be successful
Why does increasing concentration or pressure increase the rate
More particles in the same volume so more frequent collisions
Why does increasing surface area increase rate
For the same volume of the solid there is more area for the particles to collide into
How does a catalyst work
It decreases the activation energy needed by providing an alternative reaction pathway
What is the equation for rate of reaction
Rate of reaction = amount of reactant used or amount of product formed / Time
How do u test the rate of reaction with precipitates or colour changes
Place the conical flask on a white tile with a cross on it,
Add reactants and time how long it takes for the cross to no longer be visible.
Or time how long it takes for the solution to change colour
How do u measure rate of reaction with the change in mass (usually gas given off)
As gas is released, the mass that disappears is measured on the balance.
The quicker the reading the faster the reaction
How do you measure rate of reaction rate with the volume of gas given off
Uses a gas syringe to measure the volume of gas given off.
The more gas given off in a time interval, the faster the reaction
What happens when magnesium ribbon is added to dilute hydrochloric acid
Gas is given off so the mass reduces
What happens when sodium thiosulfate reacts with HCL
Produces a yellow precipitate which clouds the solution
What is equilibrium in reversible reactions
Both the forward and backward reactions happen at the same rate so there is no overall effect
When can equilibrium take place
It can only take place in a closed system where none of the reactants or products can escape
What does the position of equilibrium depend on
Temperature
Pressure
Concentration
What is Le Chatelier’s Principle
The idea that if you change the conditions of a reversible reaction at equilibrium, the system will try to counteract that change
What happens when you decrease the temperature in equilibrium
The equilibrium will move to the exothermic direction to produce more heat
What happens when you increase the pressure of equilibrium
The equilibrium tries to reduce the pressure by moving in the direction where there are fewer molecules of gas
What happens when you increase the concentration of reactants in equilibrium
It will no longer be in equilibrium so the system tries to bring it back by making more products
