Rate of Reaction

[Dark Horse]

Quick Q:
If you react 1g of Mg with a certain amount of HCl, will the rate of reaction be increased if 2g of MG is used instead? 

[Mao]

assuming the 2g piece of Mg has greater surface area, then yes. initially the rate of reaction will be greater =]

[Dark Horse]

Ah ok, if both samples of Magnesium have the same surface area, which would have a higher reaction rate? Does it have anything to do with having a high concentration of reactants? and if a volume vs concentration was plotted for both scenarios, what would the differences be/

Thanks Mao

[TrueTears]

If you have a higher concentration you increase the chances of successful collisions, hence a higher probability of the reaction occurring.

[Mao]

Ah ok, if both samples of Magnesium have the same surface area, which would have a higher reaction rate? Does it have anything to do with having a high concentration of reactants? and if a volume vs concentration was plotted for both scenarios, what would the differences be/

Thanks Mao

It all has to do with number of collisions. If both sample of magnesium have the same SA, then the number of collisions will be about the same [seeing as they are solids, not dissolved], hence there won't be much noticeable change in initial reaction rate [the reaction will just take place over a longer time because there's more to react]

[lacoste]

Is there only four main contributors to rate of reaction:

- catalyst

- heat

- surface area to vol ratio

-increasing conc

[hyperblade01]

Is there only four main contributors to rate of reaction:

- catalyst

- heat

- surface area to vol ratio

-increasing conc

I suppose this isn't a main contributor as it isn't always reasonable but something like milo in milk, you can stir it to speed up the rate of reaction

But yea, discussed it in class today and those four were the ones mainly talked about

[TrueTears]

Yes, like hyperblade said, its mainly those 4, though if you conduct an experiment and you stirred one sample, you should stir the other to be fair

[Mao]

Is there only four main contributors to rate of reaction:

- catalyst

- heat

- surface area to vol ratio

-increasing conc

it's better to understand it this way:

there are only two main contributors,

- number of collisions - the more collisions there are, the more reaction

- energy of collisions - the more energetic, the more successful a collision, the more reaction

Hence if you change the conditions and either one [or both] of the above increases, you have an increased rate of reaction.

e.g. stirring milo, you are increasing fluid velocity, hence more collisions. you are also breaking up chunks of milo stuck together, increasing surface area hence more collisions can take place.
using hot water, you are increasing energy of the particles, hence collisions are more energetic