20.181 u
The average atomic mass of Ne is the <em>weighted average</em> of the atomic masses of its isotopes.
We multiply the atomic mass of each isotope by a number representing its relative importance (i.e., its % abundance).
Thus,
Avg. at. mass
= (0.904 83× 19.992 u) + (0.002 71 × 20.994) + (0.092 53× 21.991 u)
= 18.0894 u + 0.0569 u + 2.0348 u = 20.181 u
Answer:
0.960 m
Explanation:
Given data
- Mass of the solute: 27.9 g
- Molar mass of the solute: 233.2 g/mol
- Mass of the solvent: 125.0 g = 0.1250 kg
First, we will calculate the moles of solute.
27.9 g × (1 mol/233.2 g) = 0.120 mol
The molality of the compound is:
m = moles of solute / kilograms of solvent
m = 0.120 mol / 0.1250 kg
m = 0.960 m
Answer:
(a) 
(b) 
(c) 
(d) 
Explanation:
Hello,
In this case, we define the pH in terms of the concentration of hydronium ions as:
![pH=-log([H^+])](https://tex.z-dn.net/?f=pH%3D-log%28%5BH%5E%2B%5D%29)
Which is directly computed for the strong hydrochloric acid (consider a complete dissociation which means the concentration of hydronium equals the concentration of acid) in (a) and (c) as shown below:
(a)
![[H^+]=[HCl]=0.1M](https://tex.z-dn.net/?f=%5BH%5E%2B%5D%3D%5BHCl%5D%3D0.1M)
(b)
![[H^+]=[HCl]=0.05M](https://tex.z-dn.net/?f=%5BH%5E%2B%5D%3D%5BHCl%5D%3D0.05M)

Nevertheless, for the strong sodium hydroxide, we don't directly compute the pH but the pOH since the concentration of base equals the concentration hydroxyl in the solution:
![[OH^-]=[NaOH]](https://tex.z-dn.net/?f=%5BOH%5E-%5D%3D%5BNaOH%5D)
![pOH=-log([OH^-])](https://tex.z-dn.net/?f=pOH%3D-log%28%5BOH%5E-%5D%29)

Thus, we have:
(b)

(d)

Best regards.
Igneous and <span>granite are the rocks.</span>