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Rates of Reaction
GCSE chemistry and combined chemistry
Question | Answer |
---|---|
What is the rate of a chemical reaction in terms of reactants? | How quickly the reactants in a reaction are used up |
What is the rate of a chemical reaction in terms of products? | How quickly the products in a reaction are formed |
What is the formula for a mean rate of reaction in terms of reactants? | quantity of reactant used/time taken |
What is the formula for a mean rate of reaction in terms of products? | quantity of reactant product formed/time taken |
How can you measure the quantity of a reactant or product? | In grams or in cm³ |
What are the two possible units for rate of reaction? | g/s or cm³/s (where s is seconds) |
How could you measure the rate of a reaction from a graph? | Draw a tangent to the curve and calculate the gradient. |
What is "collision theory"? | The theory that chemical reactions only occur when particles collide with sufficient energy |
What factors can affect the rate of a reaction? | Temperature, surface area of a solid, concentration or reactants in solution, pressure of gases |
State the effect of increasing the surface area on the rate of a reaction | Increases the rate |
Explain why increasing the surface area increases the rate of a reaction | More particles are available to collide, there are therefore more frequent collisions between reactants. |
State the effect of increasing the concentration on the rate of reaction | Increases |
Explain why increasing the concentration increases the rate of reaction | More concentrated means more particles in solution, therefore more frequent collisions between reactants. |
State the effect on increasing the pressure of a gas on the rate of reaction | Increases |
Explain why increasing the pressure of a gas increases the rate of a reaction | Less space for the particles to move around in, therefore more frequent collisions |
State the effect of increasing the temperature on the rate of reaction | Increases |
What is the activation energy? | The amount of energy a particle needs before it will be able to react when it collides with another particle |
Explain why increasing the temperature increases the rate of reaction | Increases the speed at which particles move therefore more frequent collisions. Increases the number of particles which have the activation energy therefore more collisions result in a reaction. |
What is a catalyst? | Something which changes the rate of a reaction but is not used up in that reaction |
What supplies the enzyme for producing alcoholic drinks | Yeast |
How do catalysts speed up reactions? | They provide another route for the reaction to take place which has a lower activation energy. |