An analytical chemist determines that an estuarine water sample contains 1.5 g/L of sulfate ion. What is the concentration in terms of (a) g/L of S (b) molar concentration of sulfate (c) normality (d) parts per million of sulfate
a) what fraction of Sulfate is S?
b) what is the mole mass of SO4?
c) What is the equivalents of SO4^-2
d) how many million water molecuses are there? How many sulfate ions are there?
(a) To determine the concentration in terms of g/L of S, we need to find the molar mass of sulfate ion (SO4^2-). The molar mass of sulfur (S) is 32.07 g/mol. Since sulfate ion has 1 sulfur atom, the molar mass of sulfate ion is 32.07 g/mol.
To convert the concentration of sulfate ion (1.5 g/L) to g/L of S, we use the molar ratio between sulfate and sulfur.
1 mol of S = 1 mol of SO4^2-
32.07 g of S = 1 mol of S
Therefore, 1.5 g of SO4^2- = (1.5 g) x (1 mol of S / 32.07 g) = 0.0467 mol of S
The concentration in terms of g/L of S is 0.0467 g/L of S.
(b) To determine the molar concentration of sulfate, we need to calculate the number of moles of sulfate (SO4^2-) present in the given concentration.
1.5 g/L of SO4^2- = 1.5 g/L x (1 mol of SO4^2- / 96.06 g) = 0.0156 mol/L of SO4^2-
Therefore, the molar concentration of sulfate is 0.0156 mol/L of SO4^2-.
(c) To determine the normality, we need to know the number of equivalent weights of sulfate ion. The equivalent weight of sulfate ion is equal to its molar mass divided by the number of positive or negative charges.
The molar mass of sulfate ion (SO4^2-) is 96.06 g/mol, and it has a charge of -2.
Equivalent weight of SO4^2- = (molar mass) / (charge) = 96.06 g/mol / 2 = 48.03 g/equivalent
Therefore, the normality of sulfate is the same as its molar concentration, which is 0.0156 N.
(d) To determine the parts per million (ppm) of sulfate, we need to calculate the mass of sulfate in 1 million parts of the solution.
1 ppm = 1 g/L
So, 1.5 g/L of SO4^2- is equal to 1.5 ppm of SO4^2-.
Therefore, the concentration in terms of parts per million (ppm) of sulfate is 1.5 ppm of SO4^2-.
To calculate the concentration of sulfate ion in different units, you need to know the molar mass of sulfate, which is 96.066 g/mol.
(a) To find the concentration in terms of grams per liter of S:
The molar mass of sulfur (S) is 32.06 g/mol. So, divide the mass of sulfate (1.5 g/L) by its molar mass:
1.5 g/L / 96.066 g/mol = 0.0156 mol/L
Therefore, the concentration in terms of grams per liter of S is 0.0156 g/L.
(b) To determine the molar concentration of sulfate:
The molar concentration is calculated by following the equation:
Molarity (M) = moles of solute / liters of solution
In this case, the moles of sulfate is given as 0.0156 mol/L.
Therefore, the molar concentration of sulfate is 0.0156 M.
(c) To calculate the normality of sulfate:
Normality is another way to express concentration, and it depends on the number of reactive species in the solute. Sulfate (SO4^2-) has a charge of -2, so its normality is twice its molarity.
Normality (N) = molarity (M) × valency factor
Since sulfate has a valency factor of 2, its normality is:
0.0156 M × 2 = 0.0312 N.
Therefore, the normality of sulfate is 0.0312 N.
(d) To find the concentration in parts per million (ppm) of sulfate:
Parts per million is a way to express concentration relative to the total amount of the solution. It is calculated as the mass of solute divided by the mass of the solution, multiplied by one million.
Concentration (ppm) = (mass of solute / mass of solution) × 10^6
Since the ratio of the mass of sulfate (1.5 g/L) to the mass of the solution (1 L) is 1.5 g/1 L:
Concentration (ppm) = (1.5 g/1 L) × 10^6 = 1,500,000 ppm
Therefore, the concentration in parts per million of sulfate is 1,500,000 ppm.