Rates of Reaction Flashcards
How would you design an experiment to investigate the effects in changes in surface area on the rate of a reaction?
React hydrochloric acid with marble chips, and change the form of the marble chips from larger pieces to smaller pieces to powder. Measure the volume of carbon dioxide produced.
How would you design an experiment to investigate the effects in changes in concentration of solutions on the rate of a reaction?
React magnesium metal with dilute hydrochloric acid and change the ratio of hydrochloric acid to water.
How would you design an experiment to investigate the effects in changes in temperature on the rate of a reaction?
React sodium thiosulfate and hydrochloric acid and time how long it takes for a black mark beneath their beaker to dissapear (a yellow precipitate is formed in the beaker). Repeat with different temperatures using a water bath.
How would you design an experiment to investigate the effects in the use of a catalyst on the rate of a reaction?
Add some manganese oxide to hydrogen peroxide and it will decompose into hydrogen and oxygen. Measure the amount of oxygen gas given off.
What is activation energy and what does it look like on an energy profile?
The minimum amount of energy necessary for chemical reactants to collide with each other (and react). This amount of energy is enough to break old bonds to form new ones.
What effect does surface area (of a solid) have on the rate of a reaction and why?
An increase in surface area also increases the rate of the reaction.
- this is because reactions can only take place on the surface of solids so more a bigger surface area increases the area for the reaction to take place
What effect does the concentration of a solution have on the rate of a reaction and why?
The more concentrated the solution, the faster the reaction.
- this is because the solution is more crowded and there are more particles in a given volume, so the frequency of successful collision increases
What effect does the pressure of gases have on the rate of a reaction and why?
The higher the pressure of the gases, the faster the reation.
- this is because when the pressure of a gas is increased, the molecule are closer together and more concentrated
- there is an increased frequency of successful collisions
What effect does the temperature have on the rate of a reaction and why?
The higher the temperature, the faster the reaction.
- This is because the particles move faster because they have more kinetic energy, so there are more successful collisions per second
What effect does the presence of a catalyst have on the rate of a reaction?
Having a catalyst speeds up the rate of the reaction.
How do catalysts speed up the rate of the reaction?
- Catalysts provide an alternative reaction pathway with lower activation energy.
- This means that the reaction doesn’t require as much energy to happen and so can happen more quickly.
