what is the molarity of 28.9 g of CaCl2 dissolved in water to make 0.78 L solutions?
To find the molarity of a solution, we need to know the number of moles of the solute (CaCl2) and the volume of the solution.
1. Calculate the number of moles of CaCl2:
The molar mass of CaCl2 is calculated as follows:
1 calcium atom (Ca) with a molar mass of 40.08 g/mol
2 chlorine atoms (Cl) with a molar mass of 35.45 g/mol each
The total molar mass of CaCl2 is:
40.08 g/mol (Ca) + 35.45 g/mol (Cl) + 35.45 g/mol (Cl) = 110.98 g/mol
To find the number of moles:
moles = mass (g) / molar mass (g/mol)
moles = 28.9 g / 110.98 g/mol
moles ≈ 0.2607 mol
2. Calculate the molarity:
Molarity (M) is defined as moles of solute per liter of solution. In this case, the volume of the solution is given as 0.78 L.
Molarity = moles of solute / volume of solution
Molarity = 0.2607 mol / 0.78 L
Molarity ≈ 0.334 M
Therefore, the molarity of the solution is approximately 0.334 M.
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). The formula to calculate molarity is:
Molarity (M) = moles of solute / volume of solution (in liters)
1. Determine the number of moles of CaCl2:
To find the number of moles, divide the mass of the CaCl2 by its molar mass. The molar mass of CaCl2 can be calculated using the periodic table.
Molar mass of CaCl2 = atomic mass of Ca + (2 x atomic mass of Cl)
The atomic masses of Ca and Cl are approximately 40.08 g/mol and 35.45 g/mol, respectively. Therefore:
Molar mass of CaCl2 = 40.08 g/mol + (2 x 35.45 g/mol)
2. Calculate the number of moles:
moles of CaCl2 = mass of CaCl2 / molar mass of CaCl2
3. Determine the volume of the solution in liters:
The problem states that the solution volume is 0.78 L.
4. Calculate the molarity:
Molarity (M) = moles of CaCl2 / volume of solution (in liters)
Now, let's plug in the values to calculate the molarity:
mass of CaCl2 = 28.9 g
volume of solution = 0.78 L
molar mass of CaCl2 = [40.08 g/mol + (2 x 35.45 g/mol)]
moles of CaCl2 = 28.9 g / [40.08 g/mol + (2 x 35.45 g/mol)]
Molarity (M) = [28.9 g / [40.88 g/mol]] / 0.78 L
Simplifying the equation, you can find the molarity of the solution.
M is moles/liter
How many moles of CaCl2 in 28.9g?
Divide that by .78L to get M