 Let's look at the effect of the state that a substance is in and the rate of the reaction. Here we're going to add some lead nitrate and some potassium iodide, both are solids at room temperature. If we put them next to each other, nothing happens. But if we take a solution of the same compounds, lead nitrate and potassium iodide and let the two bubbles run together, you notice that as soon as the water touches, the reaction occurs. So having the substance as a solution, the reaction rate is much, much faster. Here you can see if we just add water, it reacts quickly.