Answer: Increasing the concentration of a reactant or decreasing the concentration of the product.
Explanation: For the equilibrium of the reaction to shift to the left, we must decrease the concentration of a reactant or increase the concentration of the product. This is based on Le Chatelier's principle which describes the effect on the equilibrium of changes in concentration or pressure of a product or a reactant. Adding more products in a system would disturb the equilibrium thus it would cause to reestablish it by shifting the reaction to the left producing the reactants. This would also be the same when you decrease the number of reactants in the system.
<span>A cation is an atom that loses a valence electron. When a valence electron is released there is one electron less to create a repulsive force. The loss of a repulsive force will allow the atom to pull tighter together. An anion would therefore be larger in size due to increased repulsion of the valence electrons.</span>
<u>Answer:</u> The hydroxide ion concentration and pOH of the solution is 
and 2.88 respectively
<u>Explanation:</u>
We are given:
Concentration of barium hydroxide = 0.00066 M
The chemical equation for the dissociation of barium hydroxide follows:
1 mole of barium hydroxide produces 1 mole of barium ions and 2 moles of hydroxide ions
pOH is defined as the negative logarithm of hydroxide ion concentration present in the solution
To calculate pOH of the solution, we use the equation:
![pOH=-\log[OH^-]](https://tex.z-dn.net/?f=pOH%3D-%5Clog%5BOH%5E-%5D)
We are given:
![[OH^-]=(2\times 0.00066)=1.32\times 10^{-3}M](https://tex.z-dn.net/?f=%5BOH%5E-%5D%3D%282%5Ctimes%200.00066%29%3D1.32%5Ctimes%2010%5E%7B-3%7DM)
Putting values in above equation, we get:
Hence, the hydroxide ion concentration and pOH of the solution is and 2.88 respectively
