Ion Concentration Stoichiometry So just like in stoichiometry

Ion Concentration

Stoichiometry • So just like in stoichiometry when reactants change into products. Solubility is like a reaction. • Except of it changing from reactants to products, we are changing it from solid to ions • So we first have to understand how ions dissociate

Example • When we put Na. Cl into water, it dissociates into Na+ and Cl • To write it in an equation, it becomes • Na. Cl → Na+ + Cl • If we do it with Ca. Cl 2 and put it into water • Ca. Cl 2 → Ca 2+ and 2 NO 3 -

How does it work with concentration? • Remember, the coefficients just means moles. Since they are the same volume, we can just multiply our coefficients by the concentration to find our concentration of ions

Example • Ca(NO 3)2 → Ca 2+ + 2 NO 3 • If the concentration of Ca(NO 3)2 is 1. 00 M, then the concentration of Ca 2+ is 1: 1 mole ratio so it is also 1. 00 M. The concentration of NO 3 - is going to be 2: 1 mole ratio so it will be 2. 00 M. • So what if we mix two mixtures?

Example • 300. 0 m. L of 2. 00 M Na. OH is mixed with 600. 0 m. L of 5. 00 M Mg. I 2 • What is the concentration of each substance in the resulting solution? • What is the concentration of each ion in the resulting solution? • We must do our dilution equation first!

Example • 50. 0 m. L of 0. 250 M Al. Br 3 and 25. 0 m. L of 0. 300 M Ca. Br 2 are mixed together. • What is the resulting concentration of each solution? • What is the concentration of each ion?

Homework • Page 212 #30 -38 (even) • Worksheet on solution