Rates of Reaction Flashcards
Name 3 things that effect the rate of reaction?
temperature, concentration(pressure if it is gas) and size of particles
What is the formula for Rate of reaction
Amount of reactant used or the amount of product formed divided by time
Basic steps to a precipitation experiment are?
- Mix the 2 reactant solutions and put the flask on a piece of paper that has a mark on it. 2. Observe the mark through the mixture and measure how long it takes for the mark to be obscured
In an precipitation experiment disappears quickly, what does this tell us
Fast rate of reaction
What are the disadvantages of the a Participation experiment
The results are subjective. On person might see the mark disappear quicker than another
You can measure the rate of reaction that produces a gas using a mass balance. Explain
As gas is released the lost mass is easily measured on the balance. The quicker the reading on the balance drops, the faster the reaction.
You can also measure the volume of gas given off. Explain
Set up the flask with a plug and syringe, add the mixture of reactants to the flask. Set a time interval for the gas to be collected. The more gas in the set time interval, the faster the reaction
Precautions to take when collect gas in a reaction experiments
- In mass balance experiment the gas is given off into the room, so for harmful gases then us a fume cupboard. When collecting a volume of gas, make sure you use the right syringe size as vigorous reactions may blow the plug out
How does surface area affect rate of reaction
Larger surface area will increase the rate of reaction
How can you measure the surface area affecting rate of reaction
You can put various forms of Calcium carbonate in Hydrochloric Acid e.g.
Use Marble chips
then more crushed marble chips
then Chalk.
Use the same amounts of CaCO3 and HCL each time.
What does the steepness of the graph gradient indicate
Faster reaction - Steeper Gradient = faster reaction
why does changing the concentration of the reactant speed up reaction?
More reactant particles can collide with the product.
Name an experiment to test how temperature affects the rate of reaction
Use Sodium Thiosulphate and Hydrochloric Acid. The are both clear and colourless and when the react together they form a yellow precipitate of sulphur
Explain the precipitation experiment to show temperature effects rates of reaction
- Measure fixed volumes of Sodium Thiosulfate and HCL
- Use a water bath to gently heat both solutions to the desired temp before you mix them
- Mix the solutions
- Place the flask on a piece paper marks with a black mark
- Measure the time it takes for the mark to disappear
- repeat the experiment at different temperatures
What is important when conducting rate of reactions experiment
- Volume of the product is the same
- Amount of the reactant is the same
- Only change on variable at a time e.g. time or concentration or size of particle
What does the gradient of the rate of reaction graph indicate?
Steeper Gradient = faster rate of reaction
What is the gradient calculation?
Gradient = change in y divided by change in X
How to work out the change in Y
Pick two points on a graph - Draw a line straight done from the high point and then straight across (making a triangle). Read both figures from the Y axis (up) and take them away from each other
How do you work out the change in x
On the same triangle then read the first point on the x axis and the second. Take the figures away from each other.
What is collision thoery?
The is the rate of reaction
What does the reaction depend on?
The collision frequency of reacting particles (how often they collide)
The energy transferred during the collision. The minimum energy that particles need to react when they collide is called activation energy. Particle need to collide with at least the activation energy for the collision to be successful
What does more collision equal
higher rate of reactions
Why does temperature increase the reaction rate?
The particle move faster and there more collisions. Higher temperatures increase the energy of the collisions - reactions only happen if the particles collide with enough energy
Why does increasing concentration increase reaction rate
If the solution in more concentrated then there are more particles of reactant in the same volume. In gas the increase in pressure means the particles are more crowded = increase in collision
What does smaller particle (more surface area) increase reaction rate
The particles have move area to work on - more collisions = in crease in reaction rate.
