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    Hi people, just looking for some quick guidance as my exam's on Wednesday. My textbook has a straight line graph of [Reactant] (x) against Time (t). A gradient triangle is drawn underneath a line segment from two points A to B. What I'm struggling is the text underneath which says:

    "The slope of AB is exactly equal to the slope of the graph, since the graph is a straight line between A and B (fine). This graph represents a constant reaction rate - at any point between A and B, the instantaneous rate and the average rate between A and B are the same, Δ = x/Δt." (not fine) Whilst I know the difference between initial, instantaneous and average rate, I don't know what their equation means... btw the gradient triangle is labelled Δx and Δt, as expected.

    Help please?
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    (Original post by Va Sin Decir)
    Hi people, just looking for some quick guidance as my exam's on Wednesday. My textbook has a straight line graph of [Reactant] (x) against Time (t). A gradient triangle is drawn underneath a line segment from two points A to B. What I'm struggling is the text underneath which says:

    "The slope of AB is exactly equal to the slope of the graph, since the graph is a straight line between A and B (fine). This graph represents a constant reaction rate - at any point between A and B, the instantaneous rate and the average rate between A and B are the same, Δ = x/Δt." (not fine) Whilst I know the difference between initial, instantaneous and average rate, I don't know what their equation means... btw the gradient triangle is labelled Δx and Δt, as expected.

    Help please?
    x in this case is concentration

    As rate of reaction is defined as the change of concentration over time, hence the gradient = rate of reaction = change in x / change in time

    This is only true for a system where only one concentration of your reactants are changing, ie the rest are fixed. This is a technique commonly used in kinetics to determine order of reaction with respect to this specific reactant.
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    (Original post by shengoc)
    x in this case is concentration

    As rate of reaction is defined as the change of concentration over time, hence the gradient = rate of reaction = change in x / change in time

    This is only true for a system where only one concentration of your reactants are changing, ie the rest are fixed. This is a technique commonly used in kinetics to determine order of reaction with respect to this specific reactant.
    Thanks, but "Δ = x/Δt" still doesn't make sense - I know that rate = Δx/Δt but that's not what my book says.
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    (Original post by Va Sin Decir)
    Thanks, but "Δ = x/Δt" still doesn't make sense - I know that rate = Δx/Δt but that's not what my book says.
    Hmm, delta stands for a change, so I can't see why the book is stating it that way, I would probably think of it as

    change(gradient) = change in x / change in t

    I don't really know, perhaps check with your teacher, there tends to be one or two minor mistakes for most textbooks.
 
 
 
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