What is the molarity of a 28.9 g of CaCl2 dissolved in water to make up 0.78L of solution?
mols CaCl2 = grams/molar mass
M = mols CaCl2/L soln
To calculate the molarity of a solution, you need to know the amount of solute (in moles) and the volume of the solution (in liters).
Step 1: Convert the mass of CaCl2 to moles.
The molar mass of CaCl2 is:
1 atom of Ca (40.08 g/mol) + 2 atoms of Cl (35.45 g/mol) = 110.98 g/mol
To convert grams to moles, divide the mass by the molar mass:
28.9 g / 110.98 g/mol = 0.2605 mol
Step 2: Convert the volume of the solution to liters.
The volume is given as 0.78 L.
Step 3: Calculate the molarity (M).
Molarity (M) is defined as the number of moles of solute divided by the volume of the solution in liters.
M = moles of solute / volume of solution (in L)
M = 0.2605 mol / 0.78 L
Calculating this value gives:
M = 0.3338 mol/L
Therefore, the molarity of the solution is 0.3338 mol/L (or M).
To calculate the molarity (M) of a solution, you need to know the amount of solute (in moles) and the volume of the solution (in liters).
Step 1: Calculate the number of moles of CaCl2:
To do this, you will use the formula:
Number of moles = mass (g) / molar mass (g/mol)
The molar mass of CaCl2 can be calculated by multiplying the atomic mass of calcium (Ca) by 1 and the atomic mass of chlorine (Cl) by 2, then adding them together. The atomic masses can be found on the periodic table.
Molar mass of CaCl2 = (40.08 g/mol) + 2 × (35.45 g/mol)
Once you have the molar mass, you can calculate the number of moles:
Number of moles = 28.9 g / (40.08 g/mol + 2 × 35.45 g/mol)
Step 2: Calculate the molarity:
Now that you know the number of moles (n) and the volume of the solution (V), you can use the formula:
Molarity (M) = number of moles / volume of solution (in L)
Molarity = number of moles / 0.78 L
Substituting the values you calculated into the formula will give you the molarity of the solution.