One liter of Saline solution is prepared by dissolving 25.0 g NaCl in water. Find the molarity of this solution.
.....In how much water? Technically, it isn't how much water but how much solution.
moles NaCl = grams/molar mass
M = moles/L soln.
To find the molarity of the solution, you need to know the amount of solute (sodium chloride) and the volume of the solution.
Given:
- Mass of sodium chloride (NaCl) = 25.0 g
- Volume of the solution = 1 L
To calculate the molarity (M), you need to use the formula:
Molarity (M) = moles of solute / volume of solution (in liters)
To calculate the moles of solute, you need to use the formula:
moles of solute = mass of solute / molar mass of solute
The molar mass of sodium chloride (NaCl) is the sum of the atomic masses of sodium (Na) and chlorine (Cl).
The atomic mass of sodium (Na) is 22.99 g/mol, and the atomic mass of chlorine (Cl) is 35.45 g/mol.
Molar mass of NaCl = (1 * atomic mass of Na) + (1 * atomic mass of Cl)
Now let's plug in the values and solve the equations step by step:
Step 1: Calculate the molar mass of NaCl:
Molar mass of NaCl = (1 * 22.99 g/mol) + (1 * 35.45 g/mol)
Molar mass of NaCl = 22.99 g/mol + 35.45 g/mol
Molar mass of NaCl = 58.44 g/mol
Step 2: Calculate the moles of solute (NaCl):
moles of solute = mass of solute / molar mass of solute
moles of solute = 25.0 g / 58.44 g/mol
moles of solute ≈ 0.428 mol
Step 3: Calculate the molarity (M):
Molarity (M) = moles of solute / volume of solution (in liters)
Molarity (M) = 0.428 mol / 1 L
Molarity (M) ≈ 0.428 M
Therefore, the molarity of the saline solution is approximately 0.428 M.