C8 Rates and Equilibium Flashcards
How to find the rate of a reaction
Monitoring the amount of reactants used up over time
Or measuring the amount of products over time
How to find the rate of reaction on a graph
Find the gradient of a line
Draw a tangent to the curve
What is activation energy
The minimum amount of energy that particles must have in order to react, they must collide with a certain amount of energy before they can react
How does the size of the particles change the rate of reaction
The rate of a reaction increases if the surface area to volume ratio of the solid reactant increases, this increases the frequency of collisions between the particles
How do you increase the rate of reaction
Increase the frequency of reacting particles colliding with eachother
Increase the energy they have when they collide
Increase surface area : volume ratio to increase frequency of collisions
What is the equation for the mean rate
Mass of reactant used up (g)/ time
Why does increasing the temperature increase the rate of reaaction
Increasing the temperature increases the rate of reaction because particles collide more frequent and more energetically. More of the collisions ocurring in a given time results in a faster reaction because a higher proportion of particles have energy greater than the activation energy
How does concentration increase the rate of reaction
Infreasing the concentration of reactants in solution increases the frequency of collisions between particles and so increases rate of reaction
How does increasing the pressure change the rate of reaction
Increasing the pressure of reacting gases increases the frequency of collisions because the gas particles are moving faster this increases the rate of reaction
What is the lab test for oxygen
Relights a glowing splint
What is a catalyst
A chemical substance that speeds up a chemical reaction by decreasing the activation energy. It is not used up itself during the reaction
How can catalysts stop working in industry
Catalysts used in chemical plants can become ‘ poisoned ‘, and not work anymore. This happens because impurities in the reaction mixture combine with the catalyst and stop it working
What are the benefits of catalysts in industry
They increase the rate of reaction and reduce energy costs which maximises profits
What happens to the catakyst in a symbol equation
We do not include the catalyst as a reactant in a symbol equation, instead it goes above/ below the arrow leading to the products
What is an example of a reaction that includes a catalyst
2H2O2 -(catalyst)–> 2H2O + O2
Catalyst is mangenese dioxide ( MNO2 )
What is the lab test for water
White anhydrous copper sulphate turns blue
Cobalt chloride paper turns from blue to pink
What js the general formula for a reversible reaction showing the forwards and reverse reaction
Forwards reaction : A+B ⇌ C+D
Reverse reaction: C+D⇌A+B
What is the rule with energy changes in a reversible reaction
The reaction one way is exothermic and the reverse is endothermic
What is the rule with the amount of energy transferred in a reversible reaction
In any reversible reaction, the amount of energy transferred to the surroundings when the reaction goes one way is exactly equal to the energy transferred back when the reaction goes in the opposite direction
How would a reaction profile show a reversible reaction
The difference in energy between the reactants and the products will be the same for both directions of the reaction. Reaction profiles can also be used to determine which direction of the reaction is exothermic or endothermic
When does equilibrium occur in a chemical reaction
Equilibrium occurs when the reaction is in apparatus which prevents the escape of reactants and products. Equilibrium is achieved when the forwards and reverse reactions occur at exactly the same rate
What is Le Châtelier’s principle
If you change a componet in a reaction that is in dynamic equilibrium, the reaction will adjust and shift the position of equilibrium to cancel out the change and return to dynamic equilibrium
According to LC princple what would happen if the product of the forwards reaction is decreased
If the product of the forwards reaction is decreased, the forwards reaction will increase in rate ( equilbrium shifts ) to make more of the product
How does temperature effect the amount of products formed in the forwards reaction
If forwards reaction is Exothermic:
Increase - less products formed - reaction goes to endothermic to decrease temp( more reactants )
Decrease - more products formed - reaction goes to exothermic to increase temp ( less reactant )
If forwards reaction is Endothermic:
Increase - more products formed - reaction goes more endothermic to cool the temperature
Decrease - less products formed - reaction goes more exothermic to raise the temperature
How does pressure effect the amount of products in the forwards reaction of a reversible reaction
If forwards reaction produces more molecules of gas
Increase - decrease products
Decrease - increase the products
If forwards reaction produces less molecules of gas
Increase - increase products
Decrease - decrease products
What is the word equation for the Haber Process
Nitrogen + hydrogen = ammonia
Symbol equation for the haber process
N2(g) + 3H2(g) = 2NH3(g)
Where are the reactsnts for the haber processes obtained
Nitrogen: liquifying air
Hydrogen: from natural gas ( mainly methane ): methane + steam = hydrogen + carbon dioxide
What are the conditions for the Haber process and why are they those values
Pressure: 200 atmospheres, any higher pressure would cost money to make structurally sound
Temperature: 450°C, a temp lower would be better but reaction would be too slow
Catalyst: iron filings, higher surface area to volume ratio
