Chapter 8- Rates, Equilibrium and organic chemistry Flashcards
How do you find out the rate of a chemical reaction?
By monitoring the amount of reactants used up over time
What is the equation for finding the rate of reaction?
Quantity of reactant used/ time or
Quantity of product formed/ time
What can the gradient on a graph tell you about the reaction time?
It tells you the reaction time. The steeper the line the faster the reaction
How do you calculate the rate of reaction from a graph?
Draw the hypotenuse on the curved line and work out its gradient by dividing the length of the y axis by the x axis (opposite by the adjacent)
How do particles react?
By colliding with a certain amount of energy
What is the activation energy of a reaction?
The minimum amount of energy that particles must have in order to react.
What happens if the surface area to volume ratio of any solid reactants is increased what happens?
It increases the frequency of collisions between reacting particles. A larger surface are doesn’t increase the amount of reactions but simply increases the frequency of colliding particles. There are more particles in the same volume of water.
How do you measure the decreasing mass of a reaction mixture in a practical experiment?
Hydrochloric acid is put into a flask, place the flask on a weighing scale, then calcium carbonate is added and then a piece of cotton wool will be placed loosely over the flask.
Record the weight every 30s until there is no further change in mass
Practical experiment for the rate gas given off.
Attach a gas syringe to a clamp, connect the gas syringe to the bung, measure hydrochloric acid out and put into the flask attach the tube to the flask and the syringe. Take the calcium carbonate and put it in with the hydrochloric acid and attach the bung, take readings every 30s from the gas produced until no more.
Measuring the decreasing light passing through a solution?
Take sodium thiosulfate and pour it into a flask, take water and put it into another flask, in another flask have hydrochloric acid place a clean flask on paper with a cross. Combine all the substances and start timing. Tome until you cant see a cross anymore.
What is collision theory?
Particles must collide with a certain minimum energy to react
How does surface area affect the rate of reaction?
The rate of chemical reaction increases if the surface area to volume ratio increases.
It increases the frequency of the particles colliding.
How does increasing temperature increase the rate of reaction?
Particles collide more frequently and more energetically, more of the collisions occurring in a given time results in a reaction because a higher proportion of particles have energy greater than the activation energy
How does concentration affect the rate of reaction?
Increasing the concentration increases the frequency of collisions between particles, and so increases the rate reaction
How does increasing the pressure increase the rate of reaction?
It causes the frequency of collisions to increase and so increases the rate of reaction. There are more particles in the same volume of water.
What is a catalyst?
A catalyst speeds up the rate of reaction but is not used up itself during the reaction. It remains chemically unchanged. It increases the rate of reaction by reducing the activation energy of the substance
Is there one catalyst for all reactions?
No, Different catalysts are needed for different reactions
Catalysts in industry.
Catalysts are used whenever possible in industry to increase rates of reaction and reduce energy costs.
What is a reversible reaction?
In a reversible reaction, the products of the reaction can react to make the original reactants.
Give an example of a reversible reaction.
Heating ammonium chloride into gas will condense back into ammonium chloride
What are the 4 things that can affect the rate of reaction?
Temperature
Pressure/concentration
Surface area
Catalyst
What is a reversible reaction/ describe a reversible reaction.
A reversible reaction can go backwards.
e.g. A+B = C+D
A + B is reacting to form C + D
At the same time C + D is reacting to form A + B
What is equilibrium in a reversible reaction?
After a while of the reversible reaction happening the forward and backwards reaction will be happening at the same rate, this is when the system can be described as being in equilibrium.
What does it mean for the reaction when it is in equilibrium?
The forward and backwards reaction will be happening at the same time. Both reactions are still happening but there is no overall effect, it means the concentrations of the reactions have reached a balance and wont change
