C3 Flashcards
What type of reaction is rusting?
A slow reaction
What type of reactions are burning and an explosion?
Fast reactions
What does the rate of reaction measure?
The amount of product made in a specific time
For mass changes, how can the rate of reaction be measured?
g/s or g/min
For volume changes, how can the rate of reaction be measured?
cm³/s, or cm³/min
How can the rate of a reaction be increased?
By rasing the temperature, increasing the concentration (of liquids) or increasing the pressure (of gases)
When do chemical reactions stop?
When one of the reactants is used up
What does the amount of product formed in a reaction depend on?
The amount of reactant used
What is the ‘limiting reactant’ in a chemical reaction?
The one that is used up by the end of the reaction
When there are more reactants, what does this mean?
There are more reactant particles, so more product particles can be made.
What does the ‘limiting reactant’ in a chemical reaction determine?
The maximum amount of product that can be made.
How can you measure the rate of a reaction?
By monitoring the mass of a reaction mixture in a flask on a top pan balance, or measuring the volume of gas produced using a gas syringe
When do chemical reactions take place?
When particles collide with enough energy
What is the relationship between the collision of particles in a reaction and the speed of the reaction?
The more collisions there are between particles, the faster the reaction.
Why does a reaction at a low temperature cause a slow rate of reaction?
Because in a reaction at a low temperature, the particles move slowly. This means that there are less collisions between particles, and they collide with less energy, so there are less successful collisions.
Why does a reaction at a high temperature cause a fast rate of reaction?
Because in a reaction at a high temperature, the particles move fast, meaning that they collide more often and with higher energy. This results in more successful collisions.
What does increasing temperature do to particles in a chemical reaction?
It causes an increase in the particle’s kinetic energy, and so they move a lot faster.
With an increase in temperature, and therefore an increase in particle speed, what happens?
The number of collisions per second increases, and more frequent collisions between particles leads to a faster reaction
When particles collide at an increased temperature, they have more energy. What does this cause?
High energy collisions increase the chance of successful collisions: more energetic collisions lead to more successful collisions.
Why does a reaction where one or both reactants are in low concentrations cause a slow rate of reaction?
The particles will be spread out, and so they will collide less often, resulting in fewer successful collisions
Why does a reaction where one or both reactants are in high concentrations cause a fast rate of reaction?
Increasing concentration increases the number of particles in the same space, so they are all much more crowded together. The more crowded they are, the greater the chance of them colliding. This increases the number of collisions per second, and more frequent collisions leads to a faster reaction.
Why does a gas being under a low pressure cause a slow rate of reaction?
Because the particles are spread out, and so they will collide less often, resulting in fewer successful collisionsre
Why does a gas being under a high pressure cause a fast rate of reaction?
When the pressure is high, the particles are crowded more closely together. The particles collide more often, resulting in much more successful collisions (like high concentration of reactants in a solution).
What is the relationship between the surface area of a reactant and the speed of the reactant?
The larger the surface area of a reactant, the faster the reaction.
