P2 - Rates Of Reaction And Chemical Change Flashcards
What does the line in a rate of reaction graph show?
A steeper line means a faster rate of reaction
What is the collisions theory?
The more collisions means the faster the reaction. Particles have to collide with enough energy for the collision to be successful.
What are the factors affecting rate of reaction?
- Temperature (better warmer)
- Concentration or Pressure (increase is better)
- Surface area (bigger is better)
- Using a catalyst
How do you calculate rate of reaction?
Amount of reactant used or amount of product formed
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Time
How do you know if a reaction has taken place?
- A precipitation will form
- There will be a colour change
- There will be a change in mass
- Gas is given off
What do magnesium and HCl produce when reacted together and how do you know?
They produce H2 gas, we know this because there is a loss in mass.
What does sodium thiosulfate and HCl produce when reacted together?
They produce a cloudy precipitate
How do you find the mean reaction rate from a graph?
The overall change in the y value
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Total time taken for reaction
How do you find the reaction rate at a particular point on a graph?
Draw a tangent and find the gradient
What happens in the thermal decomposition of hydrated copper sulfate?
When you heat blue hydrated copper sulfate crystals it is a reversible reaction. When heated it is endothermic as the water evaporates and leaves white anhydrous copper(II). And if you add water to this white powder it goes back to blue crystals again, which is exothermic.
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 the change.
- Temperature change (decrease = exothermic; increase = endothermic)
- Pressure: only in gases (increase - moves where there are fewer molecules; decrease - moves where there are more molecules)
- Concentration (increase - makes more products; decrease - reduces amount of reactants)
