A chemist dissolves 239 mg of pure potassium hydroxide in enough water to make up of solution. Calculate the pH of the solution.
(The temperature of the solution is .) Round your answer to significant decimal places.
1 answer:
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Answer:
-- Volume of base used
--- Molarity of base
Explanation:
Given
-- Volume of acid used
--- Buret Initial reading
--- Buret Final reading
--- Molarity of the acid
Solving (a): Volume of base used (VB)
This is calculated by subtracting the initial reading from the final reading of the base buret.
i.e.
Solving (b): Molarity base (MB)
This is calculated using:
Make MB the subject
This gives:
Solving (c): <em>There is no such thing as average molarity</em>
Answer : The percent composition by volume of mixture of and
are, 18.94 % and 81.06 % respectively.
Solution :
According to the Graham's law, the rate of effusion of gas is inversely proportional to the square root of the molar mass of gas.
And the relation between the rate of effusion and volume is :
or, from the above we conclude that,
..........(1)
where,
= volume of helium gas = 29.7 ml
= volume of mixture = 9.28 ml
= molar mass of helium gas = 4 g/mole
= molar mass of mixture = ?
Now put all the given values in the above formula 1, we get the molar mass of mixture.
The average molar mass of mixture = 40.97 g/mole
Now we have to calculate the percent composition by volume of the mixture.
Let the mole fraction of be, 'x' and the mole fraction of
will be, (1 - x).
As we know that,
Now put all the given values in this expression, we get:
The mole fraction of = x = 0.1894
The mole fraction of = 1 - x = 1 - 0.1894 = 0.8106
The percent composition by volume of mixture of =
The percent composition by volume of mixture of =
Therefore, the percent composition by volume of mixture of and
are, 18.94 % and 81.06 % respectively.