What is the molarity of a solution made by dissolving 2.00g of potassium chloride (KCl) in enough water to make 150 ml of solution?
To find the molarity of the solution, you need to first find the number of moles of potassium chloride (KCl) and then divide it by the volume in liters.
Step 1: Convert the mass of KCl to moles.
The molar mass of KCl is:
K (39.10 g/mol) + Cl (35.45 g/mol) = 74.55 g/mol
Using the given mass of KCl (2.00 g):
Number of moles of KCl = Mass of KCl / Molar mass of KCl
= 2.00 g / 74.55 g/mol
Step 2: Convert the volume from milliliters to liters.
Since 1 liter is equivalent to 1000 milliliters, the volume in liters is:
Volume in liters = 150 ml / 1000
Step 3: Calculate the molarity.
Molarity (M) = Number of moles / Volume in liters
Now, you can substitute the values into the equation:
Molarity (M) = (2.00 g / 74.55 g/mol) / (150 ml / 1000)
= 0.0267 mol / 0.150 L
Calculating the final result:
Molarity (M) ≈ 0.18 M (rounded to the nearest hundredth)
Therefore, the molarity of the solution is approximately 0.18 M.
To find the molarity of a solution, we need to know the moles of solute (KCl) and the volume of the solution in liters.
First, we need to find the moles of KCl. We can calculate this using 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 approximately 39.10 g/mol, and the atomic mass of chlorine (Cl) is approximately 35.45 g/mol. Therefore, the molar mass of KCl is:
Molar mass of KCl = (1 × atomic mass of K) + (1 × atomic mass of Cl)
= (1 × 39.10 g/mol) + (1 × 35.45 g/mol)
= 74.55 g/mol
Next, we can calculate the moles of KCl using its mass and molar mass.
Moles of KCl = Mass of KCl / Molar mass of KCl
= 2.00 g / 74.55 g/mol
= 0.0268 mol
Now, we need to convert the volume of the solution from milliliters (ml) to liters (L).
Volume of solution = 150 ml = 150 / 1000 L
= 0.150 L
Finally, we can calculate the molarity (M) using the formula:
Molarity (M) = Moles of solute / Volume of solution in liters
= 0.0268 mol / 0.150 L
≈ 0.179 M
Therefore, the molarity of the solution is approximately 0.179 M.
M = mols/L
mols = g KCl/molar mass KCl
You know mols and you know L, solve for M.