C8 Flashcards
What does the rate of a reaction tell us ?
Tells us how fast a reactant turns into products
The rate of reaction can be measured in two different ways , what are they ?
- How fast a reactant is used up
- How fast a product is made
What are the three methods used to determine the rate of reaction ?
Mass loss
Gas collection
Precipitation
What does the method mass loss mean ?
It means measuring the mass loss of reactants over time
What does the method , gas collection mean ?
Measuring the amount of gas formed over time
What does the method precipitation mean ?
Measuring the formation of a precipitate over time
What is the equation used to calculate the rate of reaction ?
Rate of reaction = reactant used or product formed / time taken
State the gas collection method for rate of reaction .
When a gas is produced in a reaction it usually escapes from the reaction vessel, so the mass decreases . You do this by collecting the gas in a gas syringe and measuring the volume given off at time intervals
What equipment do you need in the gas collection method for rate of reaction ?
Conical flask , reaction mixture and gas syringe
State the method used for mass loss in rate of reaction .
You can measure the rate at which the mass of a reaction mixture changes if the reaction gives off gas. As the reaction takes place, the mass of the reaction mixture decreases.
What equipment is needed for the mass loss method in rate of reaction ?
Conical flask , scale and hydrochloric acid
When does a precipitation reaction form a solid ?
When two clear solutions are mixed together
State the precipitation method .
When a precipitation reaction happens the reaction of the mixture is covered in clouds , so if the flask is placed over a piece of paper with a cross on it, the time it takes for the cross to disappear from view can be measured .
What are the four main factors that affect the rate of chemical reactions ?
Temperature , surface area of solids , concentration of solutions or pressure of gases and the presence of a catalyst
When can reactions take place ?
When the particles of reactants come together
What is collision theory ?
The reacting particles need to collide with enough energy to cause a reaction to take place
What happens when the temperature in a reaction increases ?
The particles collide more often and collide with more energy which increases the rate of reaction
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 . The more crowded together the reactants are , the more likely they are going to collide .
How does increasing the pressure of reacting gases increase the rate of reaction ?
Increased pressure squashes the gas particles more closely together . There are more particles of gas in a given space , so increases the chance for them to react .
Why can a catalyst effect the rate of reaction ?
A catalyst can speed up the rate pf reaction and can be used over and over again
What can increasing surface be also known as ?
Decreasing solid particle size
What is activation energy ?
The minimum amount of energy needed is called the activation energy
What does a successful collison of particles entail ?
Means that the reactant of particles colliding have sufficient energy
How does increasing the surface area affect the rate of reaction ?
Increasing the surface area means that a greater surface area of particles will be exposed to the other reactant .
What is a reversible reaction ?
In some reactions the products can react together to make the original reactants again.
What symbol is used to show that an equation is reversible ?
Two arrows are used to indicate the forward and reverse reactions . The top pointing to the right and the bottom one pointing to the left .
For a reversible reaction if the reaction is exothermic in one direction , is the opposite direction exo or endo thermic ?
Endothermic , its always the opposite
Is this true in a reversible reaction , the amount of energy transferred in either direction is the same .
Yes
