What would be the resulting molarity of a solution made by dissolving 21.9 grams of KCl in enough water to make an 869-milliliter solution?
moles KCl = grams/molar mass.
Solve for moles.
Then M = moles/L.
To find the resulting molarity of a solution, we need to first calculate the number of moles of the solute (KCl) and then divide it by the volume of the solution in liters.
To calculate the number of moles of KCl, we need to convert the given mass of KCl (21.9 grams) to moles using its molar mass. The molar mass of KCl is calculated by adding the atomic masses of potassium (K) and chlorine (Cl). According to the periodic table, the atomic masses are approximately 39.10 g/mol for potassium and 35.45 g/mol for chlorine.
Molar mass of KCl = 39.10 g/mol (potassium) + 35.45 g/mol (chlorine) = 74.55 g/mol
Now, we can calculate the number of moles of KCl using the given mass and molar mass:
Number of moles = Mass / Molar mass
= 21.9 g / 74.55 g/mol
= 0.2937 mol
Next, we need to convert the volume of the solution from milliliters to liters. There are 1000 milliliters in 1 liter, so the volume of the solution in liters is:
Volume of solution = 869 mL / 1000 mL/L
= 0.869 L
Finally, we can find the molarity (M) of the solution by dividing the number of moles of solute by the volume of the solution in liters:
Molarity = Number of moles / Volume of solution
= 0.2937 mol / 0.869 L
≈ 0.338 M
Therefore, the resulting molarity of the solution made by dissolving 21.9 grams of KCl in enough water to make an 869-milliliter solution is approximately 0.338 M.