Topic 7- Rates Flashcards
1
Q
Exothermic Reaction
A
- Gives out energy
- Gives out heat
- Shown by a rise in temperature
- Mexo
2
Q
Endothermic Reaction
A
- Takes in energy
- Takes in heat
- Fall in surrounding temperature
- Bendo
3
Q
Activation Energy
A
The amount of energy required to start a reaction
4
Q
Reaction Profiles
A
Show the starting energy of the reactants and the end energy of the products
Exothermic : Reactants higher than products
Endothermic : Products higher than reactants
5
Q
Catalyst
A
- Increase the rate of a reaction
- Is not chemically changed in a reaction
- Will not change the products
- Provides an alternative reaction pathway
- Increase the rate of a reaction
6
Q
Enzymes
A
- Biological Catlysts
- Speeee up chemical reactions in living cells
- Used in protein synthesis, respiration and photosynthesis
7
Q
Rate of Reaction
A
How fast a reaction occurs. Can be worked by when all the reactants are used up or how quickly the products formed.
8
Q
How to work out rate of reaction
A
Amount of reactant used or product formed over time
9
Q
Precipitation experiment to measure rates
A
- Mixing two see through reactions forms a precipitate which clouds the solution
- Mix the two solutions on a piece of paper with an X on it
- Observe the mark until it can no longer be seen as it clouds
- The faster it disappears, the faster the rate
- This is subjective
10
Q
Changes in mass to measure rates
A
- Gas needs to be measured using a mass balance
- As gas is released, lost mass is easily measured using the mass balance
- The quicker the drop, the faster the reaction
- ## The reaction bas finished when the balance stops changing
11
Q
Gas Syringe
A
- Shows the volume of gas given off
- The more gas given off, the faster the reaction
- When no more gas is given off, the reaction has finished
12
Q
Surface area rate
A
- Use an experiment using HCl and marble chips
- Measure the volume of gas produced using a gas syringe
- Take regular time readings
- Repeat the experiment with same mass of chips but different surface areas
- The larger the surface area, the quicker the reaction
13
Q
Rates on a graph
A
- When the mass/volume produced reaches a constant, the reacton will have finished
- The steeper the gradient, the faster the reaction
14
Q
Affect of concentration on rates
A
- The higher the concentration, the faster the rate
- Same effect as surface area
15
Q
How temperature effects rates
A
- The rate can be measured by the reaction of hcl and Sodium Thiosulfate
- Both clear and when reacted from a yellow precipitate and sulfur
- Measure the amount of time it takes for the precipiate to form
- Use the X from the precipitation
- Use a water bath to heat the solution and maintain a constant
- Change the temperature to measure the time difference
