1s, 2s, 3s, 3d, 3p. huehueheuheuehuehue
Answer: 0.172 M
Explanation:
a) To calculate theconcentration of base, we use the equation given by neutralization reaction:

where,
are the n-factor, molarity and volume of acid which is 
are the n-factor, molarity and volume of base which is NaOH.
We are given:

Putting values in above equation, we get:

b) To calculate the concentration of acid, we use the equation given by neutralization reaction:

where,
are the n-factor, molarity and volume of acid which is 
are the n-factor, molarity and volume of base which is NaOH.
We are given:

Putting values in above equation, we get:

The concentration of the phosphoric acid solution is 1.172 M
Answer:
Equilibrium constant is 0.4
Explanation:
We propose the equilibrium:
PCl₅(g) ⇄ PCl₃(g) + Cl₂(g)
Initially 0.72 mol
We have the 0.72 moles of the PCl₅.
React x x x
X amount has reacted, so in the equilibrium we have:
0.72 - x 0.4 0.4
If we initially have 0.72 moles and we have 0.4 moles at the equilibrium, it means that 0.3 moles has been reacted.
Let's make the expression for Kc:
Kc = [PCl₃] . [Cl₂] / [PCl₅]
Kc = 0.4 . 0.4 / 0.4
Kc = 0.4
The balanced reaction is
3Na3PO4 + 2CuSO4 ------> 3Na2SO4 + Cu3(PO4)2
To balance this reaction of double displacement, we see first that this reaction maintain the valence numbers of every atom.
Then, to have the same value of Na in the two sides of the reaction we multiply for the number of the other side. So,
(Na3PO4)x 2
(Na2SO4)x3
As we can see either, we need to balance PO4 cause there are two molecules of this in the reactant side, so we have two molecules of PO4 in the product either.
Then we get
3Na3PO4 + 2CuSO4 ------> 3Na2SO4 + Cu3(PO4)2
To probe that balance was correct, you can verify that the charges are exactly the opposite.