How much CaCl2.6H2O and water must be weighed out to make 100 g of a solution that is 5% CaCl2 by mass?
Thanks to anyone who explains this to me
5% of 100 g is 5 g
find the moles of CaCl2 in 5 g
multiply the moles by 6 to find the amount of hydration H2O
find the mass of the hydration H2O , and add it to the 5 g of CaCl2
... this is the amount of CaCl2.6H2O needed
the rest of the 100 g is water
Thank you so much
To calculate the amount of CaCl2.6H2O and water needed to make 100 g of a 5% CaCl2 solution, we need to determine the mass of CaCl2.6H2O and the mass of water in the final solution.
Let's start by calculating the mass of CaCl2 in the final solution.
Mass of CaCl2 = 5% of 100 g = 0.05 * 100 g = 5 g
Next, we need to find the molar mass of CaCl2.6H2O. The molar mass of CaCl2 is 110.98 g/mol. The molar mass of H2O is 18.02 g/mol.
Now, let's calculate the moles of CaCl2 required.
Moles of CaCl2 = Mass of CaCl2 / Molar mass of CaCl2
= 5 g / 110.98 g/mol
= 0.04495 mol (rounded to five decimal places)
In CaCl2.6H2O, the molar mass of H2O is 6 * 18.02 g/mol = 108.12 g/mol.
Let's calculate the moles of H2O in CaCl2.6H2O.
Moles of H2O in CaCl2.6H2O = Moles of CaCl2 * 6
= 0.04495 mol * 6
= 0.2697 mol (rounded to four decimal places)
Now, we can calculate the mass of CaCl2.6H2O required.
Mass of CaCl2.6H2O = Moles of CaCl2.6H2O * Molar mass of CaCl2.6H2O
= 0.2697 mol * (110.98 g/mol + 108.12 g/mol)
= 0.2697 mol * 219.1 g/mol
= 59.1 g (rounded to one decimal place)
Finally, to calculate the mass of water required, subtract the mass of CaCl2.6H2O from the desired solution mass.
Mass of water = Desired solution mass - Mass of CaCl2.6H2O
= 100 g - 59.1 g
= 40.9 g (rounded to one decimal place)
Therefore, to make 100 g of a 5% CaCl2 solution, you need to weigh out approximately 59.1 g of CaCl2.6H2O and 40.9 g of water.
To solve this problem, we can break it down into two parts: finding the mass of CaCl2.6H2O and the mass of water needed in the solution.
Let's start by finding the mass of CaCl2.6H2O:
1. Calculate the amount of CaCl2 needed:
Since the solution is 5% CaCl2 by mass, we can calculate the mass of CaCl2 as follows:
Mass of CaCl2 = 5% * 100 g = 5 g
2. Convert the mass of CaCl2 to the mass of CaCl2.6H2O:
The molar mass of CaCl2.6H2O is 147.02 g/mol, which means that 1 mol of CaCl2.6H2O weighs 147.02 g.
Divide the mass of CaCl2 (5 g) by the molar mass to find the number of moles of CaCl2:
Moles of CaCl2 = 5 g / 147.02 g/mol
3. Calculate the mass of CaCl2.6H2O:
To find the mass of CaCl2.6H2O, multiply the number of moles (from step 2) by its molar mass (147.02 g/mol):
Mass of CaCl2.6H2O = Moles of CaCl2 * Molar mass of CaCl2.6H2O
Next, let's calculate the mass of water needed in the solution:
1. Calculate the mass of CaCl2.6H2O:
Use the mass of CaCl2.6H2O calculated from the previous steps.
2. Calculate the mass of water:
Subtract the mass of CaCl2.6H2O from the total mass of the solution (100 g):
Mass of water = Total mass of solution - Mass of CaCl2.6H2O
Now we have the mass of CaCl2.6H2O and the mass of water needed to make the solution.