Which element below is least reactive?
2 answers:
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Answer:
The correct answer is: pH= 4.70
Explanation:
We use the <em>Henderson-Hasselbach equation</em> in order to calculate the pH of a buffer solution:
Given:
pKa= 4.90
[conjugate base]= 4.75 mol
[acid]= 7.50 mol
We calculate pH as follows:
pH = 4.90 + log (4.75 mol/7.50 mol) = 4.90 + (-0.20) = 4.70
Avagadro's law gives the relationship between volume of gas and amount of moles of gas. It states that at constant temperature and pressure, volume of gas (V) is directly proportional to number of moles of gas (n).
V/n = k
where k - constant
V1 = 42.0 L
n1 = 1.90 mol
n2 = 1.90 mol - 0.600 = 1.30 mol
substituting the values in the equation
V = 28.7 L
Volume of the gas is 28.7 L
V/n = k
where k - constant
V1 = 42.0 L
n1 = 1.90 mol
n2 = 1.90 mol - 0.600 = 1.30 mol
substituting the values in the equation
V = 28.7 L
Volume of the gas is 28.7 L
It takes 33.4 s for the concentration of A to fall to one-fourth of its original value.
A <em>half-life</em> is the time it takes for the concentration to fall to half its original value.
Assume the initial concentration is 1.00 mol/L. Then,
The concentration drops to one-fourth of its initial value in two half-lives.
∴ Time = 2 × 16.7 s = 33.4 s