|What is an exothermic reaction?
|Where energy is given out (released) into the surroundings and the temperature increases.
|Give 4 examples of an exothermic reaction.
|Combustion Neutralisation Oxidation Respiration Displacement Metal and Acid
|What is an endothermic reaction?
|Where energy is taken in from the surroundings and the temperature decreases.
|Give 4 examples of an endothermic reaction.
|Photosynthesis Ice Packs Sherbet Electrolysis Thermal Decomposition
|If the reaction is reversible what would happen if it was exothermic and 400J was given out?
|The reverse would be endothermic and 400J would be absorbed.
|What is rate of reaction?
|How quickly a chemical reaction happens (speed).
|What are the two things you could measure to work out the rate of reaction?
|1) How quickly the reactant is used up or 2) How quickly a product is made
|What are the formulas to work out rate?
|rate=amount of reactant used up/time or rate=amount of product made/time
|How does gas collection work?
|A gas syringe is attached to the conical flask with the gas producing reaction. Measure the volume of gas that is produced in a certain amount of time.
|How is loss in mass measured?
|If a reaction produces a gas, its rate of reaction can be determined by measuring how quickly the mass of the reaction mixture decreases with time as the gas escapes.
|What is precipitation?
|Some reactions produce a precipitate (solid) that makes the solution go cloudy. The rate of reaction can be worked out by timing how long it takes for a solution to go cloudy.
|When the solution goes cloudy quicker is it a quick or slow reaction?
|Explain the Collision Theory
|For a chemical reaction to happen reactant particles have to collide AND the reactant particles have to have enough energy when they collide to cause a reaction.
|What is activation energy?
|The minimum amount of energy that particles need to have to cause a chemical reaction.
|Name 5 ways to change rate of reaction so they reaction can be faster/slower.
|Surface Area Concentration Pressure Temperature Catalysts
|Why is a powder better at making the reaction fast compared to lumps of the same mass?
|The larger the surface area the faster the rate of reaction.
|How does increasing the Surface Area make the reaction faster.
|Increase in SA = more frequent collisions more frequent collisions = faster reaction this is because you are exposing more particles
|What does the concentration of a solution tell you?
|How much solute is dissolved in a given volume.
|Compare low concentration with high concentration.
|Low has a small amount of solute particles but more solvent particles whereas high has a large amount of solute particles but less solvent particles.
|How does concentration affect the rate of reaction?
|When the concentration increases there are more particles in a given volume (more crowded). Because the reactant particles are more crowded, there are more frequent collisions which increases the rate of reaction.
|How does increasing pressure (on a gas) increase rate of reaction?
|The particles become more crowded because the same number of particles are squeezed into a smaller volume. This therefore makes more frequent collisions and therefore increases rate of reaction.
|Why does temperature affect rate of reaction? (two reasons)
|1) At higher temp the particles gain more energy and move faster. More frequent collisions between the reactant particles. 2) At higher temp more of the particles have the activation energy which means that there are more successful collisions between particles.
|Which would be a slower reaction? A) An 100cm³ cube B) The cube crushed into powder
|A) An 100cm³ cube