Some definitions for zero order reactions

Let s go back to our first bank account example (I will use biological examples soon, I promise). At the beginning of the year you have 300 in your current account and 0 in the savings account. How much money will there be in your current account and your savings accoimt at the end of the year We could do it by using the average rate (where we simply calculate the transfers on a monthly basis, as we have done before). But we could also use an instantaneous rate equation, in which we look at a daily, or hourly or even smaller basis. 

First of all, let s define the flow of money. If we set up a standing order to transfer money from the current account into the savings account, we can write  

We always want to transfer the same amount of money in a given period of time, e.g. a fixed sum per month, week, day or any other period of time, and hence we can write the general form of the instantaneous rate equation for this transaction  

This constant payment is usually symbolized by the letter k. k is called the rate constant for this particular reaction. 

Depending on whieh account we look at, our instantaneous rates will be very different. If we look at the eurrent aceount we withdraw money from it. Taking something away is usually indieated by a negative sign. Looking at the eurrent account, we therefore can write  

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