What is the molarity of a potassium chloride solution that has a volumeof 400.0 mL and contains 85.0 g KCl? Please show work.
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To find the molarity (M) of a solution, you need to know the amount of solute (in moles) and the volume of the solution (in liters).
First, we need to convert the mass of KCl given in grams to moles. To do this, we use the molar mass of KCl, which is the sum of the atomic masses of potassium (K) and chlorine (Cl).
The atomic mass of potassium (K) is 39.10 g/mol, and the atomic mass of chlorine (Cl) is 35.45 g/mol. Adding these two values, we find the molar mass of KCl to be:
Molar mass of KCl = 39.10 g/mol + 35.45 g/mol = 74.55 g/mol
Next, we can calculate the number of moles of KCl using the given mass and molar mass.
number of moles of KCl = mass of KCl / molar mass of KCl
= 85.0 g / 74.55 g/mol
Now, we have the number of moles of KCl. However, the volume of the solution is given in milliliters (mL), so we need to convert it to liters.
volume of solution = 400.0 mL = 400.0 mL * (1 L / 1000 mL) = 0.4 L
Finally, we can calculate the molarity (M) using the formula:
Molarity (M) = number of moles of solute / volume of solution
Molarity (M) = (85.0 g / 74.55 g/mol) / 0.4 L
Now you can substitute the values and solve for Molarity (M).