Rate Of Reaction Flashcards
What is the rate of a chemical reaction?
How fast the reactants are turned into products
What is the calculation for the rate of reaction?
amount of reactant used or amount of product formed
time
units: g/s or cm3/s
How can rate of reaction be measured?
- Mass of reaction mixture
- Volume of gas given off
- Light transmitted through solution
→ measures changes over time “quantative data”
→ cross method is subjective
What are the five things that affect the rate of reaction?
- concentration of solutions
- pressure of gas
- temperature
- surface area (of solids)
- catalysts (ish)
Describe the collision theory
Reactions only take place when the particles that make up the reactants collide with enough energy
What is activation energy?
the minimum amount of energy that particles must have when they collide before they can react
How does a higher concentration of a solution increase the rate of reaction?
There are more particles in the same volume to react with so there is an increased collisioin frequency
How does incresing the pressure of the reactants in a gas reaction increase the reaction rate?
It squashed the gas particles closer together so there are more particles in the given vollume, causing an increased collision frequency
How does a larger surface area increase the rate of reaction?
There are more of the reactant particles exposed to react with so there is a greater collision frequency
How does a higher temperature increase the rate of reaction?
- Greater collision frequency → more energy = move faster
- More successful collisions → more particles have required activation energy
What is a catalyst?
A catalyst is a substance that increases the rate of a reaction without being chemically changed or used up by the end of the reaction
How does a catalyst increase the rate of reaction?
It provides an alternate pathway for a reaction that has a lower activation energy. Thus more particles have the required EA for a successful collsion
How do catalysts help reduce costs in industrial reactions?
- Lower temperautre → less fossil fuels used
- Small amount used, doesn’t get used up
- Higher yield per unit time → increased productivity
What are some disadvantages of using a catalyst in an industrial process?
- Expensive
- Specific → different reactions need different catalysts
- Need to be regularly cleaned
(opt) Give some examples of catalysts
- Iron → Haber Process, produces ammonia
- Nickel → hydrogenation of oils, forms margarine
- Platinum → car catalytic convertors, produces CO2, N2 and water vapour
