rate constants
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Re: rate constants
Rate constants, k, should be positive since they relate given concentrations with the rate of a reaction, which will always be positive. But, if you are considering graphs, a plot of a 1st or 0 order reaction will have a slope of -k, while a plot of a 2nd order reaction will have a slope of +k.
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Re: rate constants
the rate constant (which is k) should always be positive; you can think of a rate as always positive because k (a proportion between concentrations) is positive, and rate can be presented as K[R]^n, which must be positive as negative concentration or proportions cannot exist.
on a graph of a first-order reaction, the slope is negative, but we have to add a negative sign to the overall rate to accommodate for this downward slope (the rate itself isn't negative)
on a graph of a first-order reaction, the slope is negative, but we have to add a negative sign to the overall rate to accommodate for this downward slope (the rate itself isn't negative)
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Re: rate constants
Yes, rate constants are always positive because they represent concentration and concentration has to always be positive.
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Re: rate constants
yes rate constants are always positive because even when reactions slow down or reverse, the rate from product to reactant is still moving forward, making the rate constant positive.
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Re: rate constants
Yes, rate constants are always positive because they represent concentration which is based on mass (always positive).
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Re: rate constants
Yes! Rate constants are always positive because concentrations cannot be negative values.
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Re: rate constants
Also, will we ever get a graph with a curve of lnA/t even if we have the correct order reaction? I thought I saw an example like that in the book but I was confused.
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Re: rate constants
Rate constants will be positive, but you can still get a graph with a negative slope, such as in 1st order reactions where the slope is -k.
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Re: rate constants
Since rate constants depend on concentration (which is positive), they are always positive.
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Re: rate constants
Leila_4G wrote:In what case would we ever get a negative rate constant?
for 0 or 1 order reactions in which the slope is negative!
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Re: rate constants
Rate constants are always positive because they are based off time and concentrations which are always positive.
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