Cobalt(II) chloride, a blue solid, can absorb water from the air to form cobalt(II) chloride hexahydrate, a pink solid. The equilibrium is so sensitive to moisture in the air that CoCl₂ is used as a humidity indicator.
a. Write a balanced equation for the equilibrium. Be sure to include water as a reactant to produce the hexahydrate.

Question

Cobalt(II) chloride, a blue solid, can absorb water from the air to form cobalt(II) chloride hexahydrate, a pink solid. The equilibrium is so sensitive to moisture in the air that CoCl₂ is used as a humidity indicator.
a. Write a balanced equation for the equilibrium. Be sure to include water as a reactant to produce the hexahydrate.

a. Write a balanced equation for the equilibrium. Be sure to include water as a reactant to produce the hexahydrate.

Accepted Answer

Welcome back, everyone. Hydrates are compounds that contain water in psychometric amounts. For example, copper to chloride, a brown solid can absorb water to form copper to chloride, dehydrate. A blue solid. Copper to chloride is sometimes used as a humidity indicator. Provide the balanced equation for the formation of the hydrate with water. So let's begin by writing out our reactant. We have copper to chloride. So we have our copper two plus catalon and our chloride an ion and to form copper to chloride, we would just cross the charges. So we would have C U C L sub two for copper to chloride. This is absorbing water. So we have plus H +20 as our second reactant. This is liquid and copper to clark is a solid since we know that it's a solid because it's an ionic compound. And copper is a metal and chlorine, chlorine is a non metal based on their positions on the periodic table. And so they will form a ionic compound solid here. Now, for our product, we're going to have our reaction arrow and on our product side will write out our hydrate product where we have C U C L sub two to showcase a hydrate. We're going to have a multiplication symbol or a dot here. So recall that you can use a multiple cases symbol as a dot And we have this dot And then we have di hydrate. Now notice that in our di hydrate name given in the prompt, the prefix di tells us that we have two moles of water. And so we should have the dot And then a coefficient of two and then our compound water and this copper two chloride dehydrate is also a blue solid according to the prompt. So we have a solid product. Now, we need to just compare our reactant side to our product side in order to make sure that this is balanced. Notice that on the reactant side, we have one mole of copper, two moles of chlorine, two moles of hydrogen and one mole of oxygen. On the product side, we have also one mole of copper, two moles of chlorine. We have four moles of hydrogen because we now have that coefficient of two in front of water on the product side multiplied by that subscript of two. So that gives us four and then we have also two moles of oxygen on the product side. So we're going to need to make some changes to our reacting side by adding a coefficient of two in front of our reactant water, which is now going to give us now four moles of hydrogen on the reactant side and two moles of water on the reactant side. And this is actually going to completely balance out our chemical equation with this coefficient added. And so our final answer is going to be this bounced chemical equation for the formation of our copper to chloride di hydrate. This is going to correspond with choice A and the multiple choice as our final answer. So I hope this made sense and let us know if you have any questions.

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Key Concepts

Chemical Equilibrium

Hydration Reaction

Balanced Chemical Equation