Answer:
A mole is the amount of pure substance containing the same number of chemical units as there are atoms in exactly
12 grams of carbon-12 (i.e., 6.023 X 1023).
Explanation:
J.J. Thomson hypothesized and discovered that the atom was not the smallest unit of matter but that instead there were much smaller units. He discovered "sub-atomic particles" which make up atoms. The sub-atomic particle that Thomson discovered was the electron. He discovered this through a process of experiments testing cathode rays.
The percent concentration of a solution can be calculated from; mass of solute /mass of solution * 100. The mass of the solute here is 8.1 g.
<h3>What is concentration?</h3>
The term concentration refers to the amount of solute presnt in a solution. There are many ways of expressing concentration such as molarity, molality and percentage.
Here;
mass of solution = 230.5 g
Percent of solute = 3.5 %
3.5 = x/ 230.5 * 100
3.5 = 100x/230.5
230.5(3.5) = 100x
x = 230.5(3.5) /100
x = 8.1 g
Learn more about percent concentration: brainly.com/question/202460?
<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
