First order rxns

[nshahwan 1L]

I'm a little confused on how you specifically determine if it is first order or not. Could someone explain with an example because sometimes in the book it just says it is first order and doesn't say how to get that.

[Benjamin Feng 1B]

There are a couple ways to determine this. You could graph the log of the concentration over time is linear. Or, you can check the rate to check if it is dependent only on the concentration of the reactant to the 1st power. For example, if you double the initial concentration, then the initial rate should also double, not quadruple like in a second order reaction.

[Sjeffrey_1C]

You look at the rate law to determine the order. So if the rate law is not given, they will just tell you the order so that you know which equations to use.

[ThomasNguyen_Dis1H]

You can either look at the rate law to see if there's only one concentration in it or look at a graph that graphs time as the x axis and 1/ln(concentration). If this graph makes a line with a negative slope, it is first order.

[605395381]

you can look at the rate law given or graph

[preyasikumar_2L]

You can look at the graph, the rate law expression (exponent = 1), the rate constant units (s^-1), and the equation (if there's one reactant and its stoichiometric coefficient = 1).

[Amy Kumar 1I]

If the concentration and the rate are being changed by the same factor, then it is a first order reaction.