In the modern periodic table, the elements are arranged in order of increasing atomic number. (In Mendeleev's table, they were arranged in order of increasing atomic weight). More elements are in the modern periodic table which have been discovered since Mendeleev's time.
Answer:
184 mL.
Explanation:
The following data were obtained from the question:
Initial volume (V1) = 62.8 mL
Initial concentration (C1) = 167 μM
Final concentration (C2) = 57.0 μM
Final volume (V2) =?
To obtain the final volume of the solution, we shall apply the dilution formula as follow:
C1V1 = C2V2
167 × 62.8 = 57 × V2
10487.6 = 57 × V2
Divide both side by 57
V2 = 10487.6 / 57
V2 = 183.99 ≈ 184 mL
Therefore, chemist must add distilled water to the solution until it reaches a volume of 184 mL.
Used mainly in the context of Geography a Constructive force is involved in making new land while a Destructive force breaks the land. As they are carrying opposite functions to one another they are considered as competing forces.
Answer:
A 0.001 molar solution of weak acid has a pH = 4.0,The pKa is :
B. 5
Explanation:
pH = It is negative logarithm of hydrogen ion concentration.
pH = -log([H+])
Ka = It is the dissociation constant.
pKa = -log(Ka)
<u>The acid dissociates according to the equation given below:</u>
Here , The concentration of A- and H+ will be same
So,
[H+] = [A-].....(1)
Now ,
pH = 4.0
pH = -log([H+])
4.0 = -log([H+])
- 4.0 = log([H+]) take antilog both side::"use scientific calculator"
From equation (1), [A-] =
[HA] = 0.001 M (given)
Insert the value of HA , H+ and A- in Ka
pKa = -log(Ka)
pKa = 5