Figure 1

Graphical Abstract: At a given supersaturation state, the conventional affinity-based rate law predicts a rate that is independent of the ion ratio (green horizontal line). However, the ion activity ratio influences the instantaneous rate, changes in the rate over time, and the nature of precipitation kinetics at extreme ion ratios. Calcite precipitation rate as a function of ion activity ratio at constant composition and supersaturation (Ω = 9.4 ± 0.5). Error bars represent the standard error. The dashed line represents a simple kinetic model of the experimental data, discussed in the text.