First, you want to extract the negative from -log(x).
So now you have log(x) = -2
Now you have to use the property loga(x)=b is the same as x=a^2
So now, it is x = 10^-2. Remember that when there is just a log, it is implied that it is ‘a’ is 10.
Then you evaluate the negative square to 1/10^2
Answer is 1/100
Answer : The number of grams of solute in 500.0 mL of 0.189 M KOH is, 5.292 grams
Solution : Given,
Volume of solution = 500 ml
Molarity of KOH solution = 0.189 M
Molar mass of KOH = 56 g/mole
Formula used :

Now put all the given values in this formula, we get the mass of solute KOH.


Therefore, the number of grams of solute in 500.0 mL of 0.189 M KOH is, 5.292 grams
Given :
A compound has a molar mass of 129 g/mol .
Empirical formula of compound is C₂H₅N .
To Find :
The molecular formula of the compound.
Solution :
Empirical mass of compound :

Now, n-factor is :

Multiplying each atom in the formula by 3 , we get :
Molecular Formula, C₆H₁₅N₃
The concentration of mixed solution = 0.5 M
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Further explanation
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Given
0.5 M HCl
0.5 M Ca(OH)₂
Required
The concentration
Solution
Molarity from 2 solutions :
Vm Mm = V₁. M₁ + V₂. M₂
m = mixed solution
V = volume
M = molarity
V = mixed volume
1 = solution 1
2 = solution 2
Vm = V₁+V₂
Equal volumes⇒V₁=V₂, and Vm = 2V, then equation becomes :
2V.Mm = V(M₁+M₂)
2V.Mm = V(0.5+0.5)
Mm=0.5 M