The Rate And Extent Of Chemical Change Flashcards
For a chemical reaction to happen:
reactant particles
must collide with each other
the particles must have enough energy for them to react
The mean rate of reaction can be calculated using either of these two equations:
Mean rate of reaction=
quantity of reactants used/time taken
Mean rate of reaction=
quantity of products made/time taken
The gradient of the line is equal to the rate of reaction:
the steeper the line, the greater the rate of reaction
fast reactions - seen when the line becomes horizontal - finish sooner than slow reactions
If the concentration of a reacting
solution or the pressure of a reacting gas is increased:
the reactant particles become more crowded the frequency of collisions between reactant particles increases
the rate of reaction increases
If a large lump is divided or ground into a powder:
its total volume stays the same
the area of exposed surface increases
the surface area to volume ratio increases
If the surface area to volume ratio of a reacting solid is increased:
more reactant particles are exposed at the surface
the frequency of collisions between reactant particles increases
the rate of reaction increases
If the temperature of the reaction mixture is increased:
reactant particles move more quickly the energy of the particles increases
the frequency of successful collisions between reactant particles increases
the proportion of collisions which are successful increases
the rate of reaction increases
A catalyst is a substance that:
increases the rate of a reaction does not alter the products of the reaction is not chemically changed or used up at the end of the reaction
What catalysts in biological reactions called
Catalysts in biological reactions are called enzymes. Catalysts do not appear in the overall chemical equation for a reaction.
How can reversible reactions be represented:
A + B ⇌ C + D the forward reaction is the one that goes to the right
the backward reaction is the one that goes to the left
