When ionic solids dissolve in water, they produce soluble aqueous cations and anions. For example, adding MgBr2 solids to water will produce ions according to the dissolution reaction below.

Question

MgBr₂(s) → Mg²⁺(aq) + 2 Br⁻(aq)

cation Anion

In this lab, you will be observing the color of emission from ions dissolved in solution. Please write the dissolution reaction for each of the ionic solids below. (Use the lowest possible coefficients. Include states-of-matter under the given conditions in your answer.)

LiNO₃

CaCl₂

Ba(NO₃)₂

Answer 1

You are already given an example of how to write the dissolution reaction equations. The formula of the compound reflects how many moles of ions are present when the substance ionizes if the substance is soluble. Another good to to reflect on is how the formula of the compound was obtained and if these compounds are soluble or not...

LiNO_{3 (s)} is made up of Li ion and the nitrate ion (polyatomic ion). It is a soluble salt so following the example given above the answer would be LiNO_{3 (s)} → Li ⁺ _(aq) + NO₃ ‾ _(aq)

You should be able to identify the cations and the anions!

Remember if you have a formula with a polyatomic ion, it stays intact and also if the formula has the ion in parenthesis, it indicates how many of the ions are involved in the formula. For formulas such as CaCl₂ , the 2 indicates that there are 2 moles of Cl ‾ ions present

I suggest you review the information mentioned above and hope this helps!