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# Units for Rate constant (k) watch

1. Hey, so I did an experiment recently for which I need to find the rate equation. I know in principle how to work out the units for K but my units seems rather bizarre... My experiment involved collecting hydrogen gas in a syringe so my initial rate of reaction was in ml s-1. The concentration of my acid was mol dm3

So I get k = ml s-1/mol dm3. None of that cancels and I'm sure mol dm3 ml s-1 doesn't work as units D:

Can anyone see where I'm going wrong? THANK YOU!
2. Can you write out your rate equation in terms of reactants (or products)? Then you can check whether the units balance.

Can you also think of how you may get rid of the units ml? What is a ml in terms of metres?
3. I think I've figured it out! 1 ml = 1 cm3 and 1cm3 = 0.001 dm3
So if I convert ml to dm3 that should cancel out to an extent? Getting my brain in knots about when it's supposed to be dm-3 ... I can never remember what thoe minus sign is for >.<
4. Hi,

I am doing an chemistry investigation (Bromate, bromide and hydrogen Ions reaction). The problem is that I have calculated the reaction rate in 1/time which gives me units s-1. However I have seen some examples of reaction equation and they include mol dm-3 s-1. In those example the table included 1/time as rate of reaction but when calculating the reaction constant k, they put units of rate of reaction as mol dm-3 s-1 even though the magnitude is exactly same as 1/time.

My question is how to change the units of reaction rate from s-1 to mol dm-3 s-1. I don't think it is just a matter of multiplying concentration with 1/time.

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Updated: March 26, 2013
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