What is the molarity of a solution composed of 8.210g of Potassium Chromate (K2CrO4),dissolved in enough water to make .500 L of solution
To find the molarity of a solution, you will need to use the formula:
Molarity (M) = moles of solute / volume of solution (in liters)
First, let's calculate the number of moles of Potassium Chromate (K2CrO4) using its molar mass. The molar mass of K2CrO4 is calculated by adding up the atomic masses of each element in the compound.
Molar mass of K2CrO4:
(2 * molar mass of K) + (1 * molar mass of Cr) + (4 * molar mass of O)
(2 * 39.1 g/mol) + (52.0 g/mol) + (4 * 16.0 g/mol)
78.2 g/mol + 52.0 g/mol + 64.0 g/mol
194.2 g/mol
Next, we need to convert the given mass of K2CrO4 (8.210 g) to moles using the formula:
moles = mass / molar mass
moles = 8.210 g / 194.2 g/mol
Now, let's calculate the molarity of the solution using the formula mentioned above:
Molarity (M) = moles of solute / volume of solution
Since the volume of the solution is given as 0.500 L, we can substitute the values:
Molarity (M) = (8.210 g / 194.2 g/mol) / 0.500 L
Now it's time to calculate:
Molarity (M) = (0.04224 mol) / 0.500 L
Molarity (M) = 0.0845 M
Therefore, the molarity of the solution is 0.0845 M.
To find the molarity of a solution, you need to know the number of moles of the solute (Potassium Chromate in this case) and the volume of the solution in liters.
To find the number of moles of Potassium Chromate, you can use its molar mass, which is calculated by adding up the atomic masses of the atoms in the compound. The atomic masses of Potassium (K), Chromium (Cr), and Oxygen (O) are approximately 39.10 g/mol, 52.00 g/mol, and 16.00 g/mol, respectively.
The molar mass of Potassium Chromate (K2CrO4) is:
(2 x molar mass of Potassium) + molar mass of Chromium + (4 x molar mass of Oxygen)
= (2 x 39.10 g/mol) + 52.00 g/mol + (4 x 16.00 g/mol)
= 39.10 g/mol + 52.00 g/mol + 64.00 g/mol
= 115.10 g/mol
Now, you can calculate the number of moles of Potassium Chromate using its mass (8.210 g) and the molar mass:
moles = mass / molar mass
= 8.210 g / 115.10 g/mol
≈ 0.071 moles
Finally, you can calculate the molarity of the solution by dividing the number of moles of the solute (Potassium Chromate) by the volume of the solution in liters:
Molarity (M) = moles / volume(L)
= 0.071 moles / 0.500 L
= 0.142 M
Therefore, the molarity of the solution is approximately 0.142 M.