Reaction Rates Flashcards
what is the rate of a reaction
how quickly a reaction happens
what are the two ways that the rate of reaction can be measured
- by measuring how quickly the reactants are used up
- or measuring how quickly the product is formed
what is the formula for calculating the rate of reaction
rate of reaction = how much of the reactants are used up or how much product if formed / time
what are the 3 experimental measurements used to measure rate of reaction
- precipitation
- change in mass
- volume of gas given off
what type of reactions would the method of precipitation work in
- any reaction where mixing two see-through solutions produces a precipitate
- which clouds the solution
how is the method of precipitation carried out
how is the method of precipitation carried out
what is the rate at which the mixture obscures the mark in the precipitation method measuring
- the rate of reaction between the two solutions
- when they react, a precipitate is formed which clouds the solution
if the mark on the paper quickly disappears in the precipitation method, what does it indicate
a quick reaction, so the rate of reaction is high
what is a disadvantage of the precipitation method
- the result is subjective
- different people might not agree on exactly when the mark disappears
what is a mass balance used for
measuring the rate of a reaction that produces a gas
while measuring the change in mass, how does a mass balance indicate the rate of a reaction
- during reaction, as gas is released
- lost mass is easily measured on the balance
- the quicker the reading on the balance drops, the faster the reaction
ho do you know when a reaction has finished in the change in mass method and why
- when the reading on the balance stops changing
- because no more mass is being lost
- so no more gas is being released
- meaning the reaction has stopped
how can your results in the change in mass method be visually displayed
by plotting a graph of change in mass against time
what is a disadvantage of the change in mass method
- method releases gas produced into the room
- if gas is harmful, safety precautions must be taken
why would you put cotton wool in the mouth of a flask during the change in mass method
- the cotton wool let’s gases through
- but stops any solid, liquid or aqueous reactants flying out during the reaction
how is the volume of gas given off in the ‘volume of gas given off’ method measured with
a gas syringe
how is a faster reaction indicated in the volume of gas given off method
- more gas is given off during a set time interval
- shown by the gas syringe filling up at a quicker rate
how can you tell when the reaction has finished in the volume of gas given off method
when no more gas is produced and the gas syringe reading doesnt change
how would you plot your results on a graph from the volume of gas given off method
you would plot the graph of gas volume against time elapsed
what is a disadvantage of the volume of gas given off method
- need to be careful using youre the right size gas syringe
- if reaction is too vigorous, the plunger can be blown off the end of the syringe