C2b Flashcards
What 4 things does rate of reaction depend on?
Temperature, concentration/pressure, catalyst, surface area (solids)
What are the 2 ways rate of reaction can be measured?
How quickly reactants are used up
How quickly the products are formed
What is the formula for rate of reaction?
Amount of reactant used/product formed ÷ time
What 3 things can rate of reaction be measured by?
- Precipitation- cloudy solution- cross under flask
- Change in mass- gas given off- mass balance
- Volume of gas given off- gas syringe
What are the 3 rate of reaction experiments and what do they measure?
- Hydrochloric acid and marble chips- gas given off
- Reaction of magnesium metal with hydrochloric acid- change in mass
- Sodium thiosulfate and hydrochloric acid- precipitation
What is the collision theory?
The more collisions in particles = the faster the rate of reaction
What 3 things increase collisions and why?
- Higher temperature- more kinetic energy so particles move quicker
- Higher concentration/pressure- more particles of reactant knocking water particles/pressure means particles are squashed together
- Larger surface area- particles around it in solution will have more area to work on
Reactions can only happen if…
particles collide with enough energy
What’s a catalyst?
A substance that speeds up the rate of reaction without changing it or being used up in the reaction
How does a solid catalyst work?
It gives the reacting particles something to stick to, increasing the number of successful collisions
How do catalysts reduce costs in industrial reactions?
They increase the rate of reaction- this saves money because plants and machines don’t need to operate for as long. The reaction can operate at a lower temperature which reduces energy needed- saves money/sustainable
What are the disadvantages of using catalysts in the industry?
- Expensive to buy
- Need to be removed from product and cleaned
- Different reactions need different catalysts
- Can sometimes be poisoned by impurities so they stop working
What’s an exothermic reaction?
One which transfers energy to the surroundings, usually in the form of heat and is shown by a rise in temperature
What’s an example of an exothermic reaction?
Burning fuels (combustion)
What everyday items use exothermic reactions?
Handwarmers/self heating cans
What’s an endothermic reaction?
One which takes energy from the surroundings (in the form of heat) and is shown by a fall in temperature
What’s an example of an endothermic reaction?
Thermal decompositions
What everyday items use endothermic reactions?
Sports injury ice packs
In a reversible reaction, if a reaction is endothermic in one direction, it will be…
exothermic in the other direction
What is the pH scale and what does it go up to?
A scale used to measure how acidic or alkaline a solution is, it goes from 0-14