Steam
Hazard to Others
Posts: 238
Registered: 25-3-2014
Location: Minnesota
Member Is Offline
Mood: Triple Point
|
|
Reaction rates
Hello, I am trying to do a school lab on the reaction rate constant "k" on the addition of Mg to HCl. I know that the rate law law for a first order
rxn is ln[A]=-kt+ln[Ao] and the second order rxn (1/[A])=(1/[Ao])+kt. I am trying to solve for k. I am ale to change the concentration of the HCL
solution but I was wondering how I would change the concentration of the Mg to determine if the reaction was first or second order?
DISCLAIMER: The information in this post is provided for general informational purposes only and may not reflect the current law in your jurisdiction.
No information contained in this post should be construed as legal advice from the individual author, nor is it intended to be a substitute for legal
counsel on any subject matter. No reader of this post should act or refrain from acting on the basis of any information included in, or accessible
through, this post without seeking the appropriate legal or other professional advice on the particular facts and circumstances at issue from a lawyer
licensed in the recipient’s state, country or other appropriate licensing jurisdiction.
|
|
|
Galinstan
Hazard to Self
Posts: 53
Registered: 22-11-2013
Location: England
Member Is Offline
Mood: No Mood
|
|
to determine the rate with respect to the magnesium just change the mass of magnesium used while keeping the concentration of HCl the same and measure
the time it takes for all the Mg to dissolve. while at the same time measure the volume of H2 gas evolved to work out the rate at which the magnesium
is being dissolved. hope this helps
|
|
|
Steam
Hazard to Others
Posts: 238
Registered: 25-3-2014
Location: Minnesota
Member Is Offline
Mood: Triple Point
|
|
That does.
Could the rate that the Mg is dissolved be accurately determined by the change of PH in the HCl solution?
DISCLAIMER: The information in this post is provided for general informational purposes only and may not reflect the current law in your jurisdiction.
No information contained in this post should be construed as legal advice from the individual author, nor is it intended to be a substitute for legal
counsel on any subject matter. No reader of this post should act or refrain from acting on the basis of any information included in, or accessible
through, this post without seeking the appropriate legal or other professional advice on the particular facts and circumstances at issue from a lawyer
licensed in the recipient’s state, country or other appropriate licensing jurisdiction.
|
|
|
DraconicAcid
International Hazard
Posts: 4278
Registered: 1-2-2013
Location: The tiniest college campus ever....
Member Is Offline
Mood: Semi-victorious.
|
|
You cannot change the concentration of magnesium in this reaction. The rate of the reaction will not depend on the mass of magnesium present, but on
its surface area, which will not remain constant as the reaction proceeds (particularly if you're using magnesium ribbon or turnings).
Please remember: "Filtrate" is not a verb.
Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
|
|
|
Steam
Hazard to Others
Posts: 238
Registered: 25-3-2014
Location: Minnesota
Member Is Offline
Mood: Triple Point
|
|
so then this reaction has to be a first order reaction?
DISCLAIMER: The information in this post is provided for general informational purposes only and may not reflect the current law in your jurisdiction.
No information contained in this post should be construed as legal advice from the individual author, nor is it intended to be a substitute for legal
counsel on any subject matter. No reader of this post should act or refrain from acting on the basis of any information included in, or accessible
through, this post without seeking the appropriate legal or other professional advice on the particular facts and circumstances at issue from a lawyer
licensed in the recipient’s state, country or other appropriate licensing jurisdiction.
|
|
|
DraconicAcid
International Hazard
Posts: 4278
Registered: 1-2-2013
Location: The tiniest college campus ever....
Member Is Offline
Mood: Semi-victorious.
|
|
No- I don't know what the order will be with respect to the acid. It may be first order, it may be second order, it may be more complicated. But the
variation in surface area of your magnesium is going to make this experiment very tricky indeed. You would need to use a large piece of clean
magnesium to make sure you have the same surface area in all of your trials.
Please remember: "Filtrate" is not a verb.
Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
|
|
|
Steam
Hazard to Others
Posts: 238
Registered: 25-3-2014
Location: Minnesota
Member Is Offline
Mood: Triple Point
|
|
Could varying the amount of mg turnings added determine the rate law with respect to the Mg?
DISCLAIMER: The information in this post is provided for general informational purposes only and may not reflect the current law in your jurisdiction.
No information contained in this post should be construed as legal advice from the individual author, nor is it intended to be a substitute for legal
counsel on any subject matter. No reader of this post should act or refrain from acting on the basis of any information included in, or accessible
through, this post without seeking the appropriate legal or other professional advice on the particular facts and circumstances at issue from a lawyer
licensed in the recipient’s state, country or other appropriate licensing jurisdiction.
|
|
|
DraconicAcid
International Hazard
Posts: 4278
Registered: 1-2-2013
Location: The tiniest college campus ever....
Member Is Offline
Mood: Semi-victorious.
|
|
Not unless you can measure the surface area of the turnings. This sounds tough, but it's even harder if the turnings aren't perfectly free of oxide
coatings.
It would be much easier to work with a one-phase reaction, with everything in solution, rather than attempting to find the rate law for a two-phase
reaction.
Please remember: "Filtrate" is not a verb.
Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
|
|
|
Steam
Hazard to Others
Posts: 238
Registered: 25-3-2014
Location: Minnesota
Member Is Offline
Mood: Triple Point
|
|
Got it, I think I am just going to do the rate in terms of the HCl concentration.
DISCLAIMER: The information in this post is provided for general informational purposes only and may not reflect the current law in your jurisdiction.
No information contained in this post should be construed as legal advice from the individual author, nor is it intended to be a substitute for legal
counsel on any subject matter. No reader of this post should act or refrain from acting on the basis of any information included in, or accessible
through, this post without seeking the appropriate legal or other professional advice on the particular facts and circumstances at issue from a lawyer
licensed in the recipient’s state, country or other appropriate licensing jurisdiction.
|
|
|
![[*]](images/xpblue/default_icon.gif){kind=icon}
