C8 Flashcards
You can compare solids wth different surface areas quantitatively by looking at their _____
surface area to volume ratio
Why is reaction rate important in the chemical industry?
To make sure products are made quickly and cheaply
Why is it cheaper to use catalysts?
Because otherwise to get the same reaction it would require higher temperatures and/or pressures every time
Why is food cooled?
To slow unwanted chemical reactions
Why is chemical equilibrium described as dynamic?
Both forward and backward reactions still happen
Why does increasing the concentration of reactants in a solution increase the rate of reaction?
Because there are more particles of the reactants moving around in the same volume of solution.
When has a state of dynamic equilibrium been reached?
When the forward and reverse reactions are continously taking place
What types of metals are catalysts often?
Very expensive metals like gold, platinum and palldium
What piece of apparatures could be used to measure the volume of gas produced in a reaction?
A gas syringe
What is used to show that a reaction is reversible?
Two ‘half-arrows’
What is the rate of reaction?
How fast reactants turn into products
What is the method to investigate the effect of changing concentration on the rate of reaction by measuring the volume of gas given off?
- Measure 50 cm3 of 1.0 mol/dm3 H2SO4 solution into a flask
- Add the magnesium ribbon to the flask and connect it to the gas collection equipment
- Start the stopwatch and record the volume of gas every 10 seconds
- When the reaction is complete, repeat using 1.5 mol/dm3 sulfuric acid
What is the conclusion for the practical to investigate reaction rate by measuring gas volume?
As there are more reactant particles in a given volume collisions occur more frequently, increasing the rate of reaction
What is reaction rate important in?
The chemical industry and your body
What is Le Chateilier’s Principle?
Where you can change the relative amounts of the reactants and products in a reacting mixture at equilibrium by changing the conditions
What is collision theory?
The reacting particles do not only have to bump into each other but also need to colldie with enough energy to cause a reaction to take place
What is a catalyst?
A substance that changes the rate of a reaction without being changed chemically itself
What has a greater effect on the rate of reaction than the increased frequency of collisions?
An increased proportion of particles exceeding the activation energy
What happens when you heat ammonium chloride?
It’s broken down into ammonium gas and hydrogen chloride gas, but when the gases cool down they recombine to form the white solid ammonium chloride again
What happens when particles collide more frequently?
There are more chances for them to react, increasing the rate of reaction
What happens to catalysts used in chemical plants?
They can eventually become ‘posioned’ so they do not work anymore, because of the impurities in the reaction mixture which combine with the catalyst
What happens to a reversible reaction at equilibrium if the pressure is decreased?
The position of equilibrium will shift to favour the reaction that produces the most gas molecules