topic six: rate and extent of chemical change Flashcards
give the equations regarding mean rate of reaction
mean rate of reaction = quantity of reactant used / time
mean rate of reaction = quantity of product formed / time
what can the quantity of a chemical be measured in?
mass in grams / volume of gas in cm3 / amount in moles
why do we draw reaction rate graphs?
they can be drawn to show how the quantity of reactant used or product formed changes with time
what does the slope represent in a reaction rate graph?
the rate of reaction thus the steeper the slope, the faster the reaction
how would we find the rate of reaction at a single point?
by drawing a tangent to the curve and calculating the slope
what is the formula for calculating the slope?
change in y / change in x
define activation energy
the minimum amount of energy particles need to react
when do successful collision occur?
when reactant particles collide with enough energy to react
what does the rate of a reaction depend on? (regarding collision theory)
the frequency of successful collisions
how does temperature influence the rate of a reaction?
the higher the temperature, the faster the reaction. this is because the particles have more energy so they have enough energy to react when the collide
how does concentration influence the rate of a reaction?
the higher the concentration, the more particles of a solute that are dissolved. the higher the concentration of reactant in solution, the greater the rate of reaction. this is because there are more reactant particles in the solution meaning a successful collision is more likely to occur.
how does the pressure of reacting gases influence the rate of a reaction?
the greater the pressure of a gas, the closer the reactant particles are together so the higher the pressure the faster the reaction. this is because the reactant particles are closer together so there are more frequent successful collisions.
how does surface area of solid reactant influence the rate of a reaction?
when a solid is in powder form, it has a greater surface area. the greater the surface area, the faster the rate of reaction. this is because there are more particles on the surface that can react so there are more frequent successful collisions.
how does the presence of a catalyst influence the rate of a reaction?
when a catalyst is present, the activation energy is lowered meaning the particles require less energy to react and thus do so more frequently.
define a catalyst
a substance that speeds up a chemical reaction without getting used up in the process