Example 6

[p1yu5h]

Hello,

I am a second year undergraduate student and I am trying to learn PHREEQC from examples. In example 6 of PHREEQC, can someone please clarify regarding whether they are takin the pure water for every simulation or are they using the same beaker cumulatively?

If they are using pure water each time then why is the graph obtained continuous?

[dlparkhurst]

Unless the keyword INCREMENTAL_REACTIONS is included (which it is not), all calculations start with the defined SOLUTION for a "simulation". A simulation is the code defined between END statements.

In 6B, there is a REACTION definition with multiple steps, each with increasing amounts of K-feldspar added to solution 1. Each reaction amount is added to pure water (solution 1). If you connect the corresponding points on the graph, it looks continuous.

Similarly in 6C, there are increasing lengths of time steps that can be connected on a graph. Each reaction integrates from time 0 to the time indicated. (For long simulations, it is better to use INCREMENTAL_REACTIONS so that the integrations start at the previous cumulative time, rather than from time 0.)