Answer:
pKa = 3.675
Explanation:
∴ <em>C</em> X-281 = 0.079 M
∴ pH = 2.40
let X-281 a weak acid ( HA ):
∴ HA ↔ H+ + A-
⇒ Ka = [H+] * [A-] / [HA]
mass balance:
⇒<em> C</em> HA = 0.079 M = [HA] + [A-]
⇒ [HA] = 0.079 - [A-]
charge balance:
⇒ [H+] = [A-] + [OH-]... [OH-] is negligible; it comes from to water
⇒ [H+] = [A-]
∴ pH = - log [H+] = 2.40
⇒ [H+] = 3.981 E-3 M
replacing in Ka:
⇒ Ka = [H+]² / ( 0.079 - [H+] )
⇒ Ka = ( 3.981 E-3 )² / ( 0.079 - 3.981 E-3 )
⇒ Ka = 2.113 E-4
⇒ pKa = - Log ( 2.113 E-4 )
⇒ pKa = 3.675
Atomic number
Explanation:
The atomic number is enough clue that can be used to proper place elements without any other information. The atomic number is the number of protons in an atom. Protons are positively charged particles in the nucleus of an atom.
- To place elements on the periodic table, the periodic law which states that "properties of elements are a periodic function of their atomic number" must be obeyed.
- Using the atomic number, one can determine the number of electrons in a neutral atom, the charges on an ion e.t.c.
- Atomic number can also be used to write the electronic configuration of an atom be it the shell notation, sublevel notation and the lewis dot structure.
Learn more:
Atomic numbers brainly.com/question/5425825
About atomic numbers brainly.com/question/1379579
Electronic configuration brainly.com/question/549647
#learnwithBrainly
Answer:
CuFeS2
Explanation:
Calculate the moles of each substance by doing moles= mass/relative atomic mass. you should get 0.25 moles of copper and iron and 0.5 moles of sulfur. Then divide all of those numbers by 0.25 (as its the lowest value) you should get 1 for copper and iron and 2 for sulfur. This represents the ratio that they are in within the mineral.
Answer:
A) 2.69 M
B) 0.059
Explanation:
A) We have:
33.8% solute by mass= 33.8 g solute/100 g solution
molarity = mol solute/ 1 L solution
molarity= 
x 
x 
x 
molarity= 2.69 mol solute/L solution = 2.69 M
B) We know that there are 33.8 g of solute in 100 g of solution.
As the total solution is compounded by solute+solvent (in this case, solvent is water), the mass of water is the difference between the mass of the total solution and the mass of solute:
mass of water= 100 g - 33.8 g = 66.2 g
Now, we calculate the number of mol of both solute and water:
mol solute= 33.8 g solute x 
= 0.232 mol
mol H20= 66.2 g H₂O x 
Finally, the mol fraction of solute (Xsolute) is calculated as follows:
Xsolute=
Xsolute= 0.059
The calculation is (Measurement in m³ x 1000³)
Therefore
Measurement in m³ x 1 000 000
Its not a fraction as there are 1000mm in a m, so to convert from m to mm you must multiply
