Consider the HF solution with the concentration of 5%(w/v). You can convert the % concentration into the molarity.
a) Assume that you have 100ml of this solution. Determine the number of moles of HF if the concentration of HF is given as 5%(w/v)
For this part I did
5% is 5g
5gHF in 100ml, (am I suppose to convert 100 ml, if yes to what pls)
then molar mass of HF is 20g/mol
am i dividing half of 100 with the molar mass or what do I do
b) Determine the molarity of HF by using the moles of HF from question (a) and the volume of the solution that you assumed in (a)
a. mols HF = grams/molar mass = 5/20 = ? about 0.25 mols
b.
Then M = mols/L = 0.25 mols/0.1 L = ?
To calculate the number of moles of HF in the solution, you follow these steps:
a) Determine the number of grams of HF in the solution.
- You correctly identified that 5% (w/v) means that there are 5 grams of HF in every 100 milliliters of solution.
- So, if you have 100 milliliters of solution, then you have 5 grams of HF.
b) Convert the grams of HF to moles of HF.
- To do this, you need to know the molar mass of HF, which is 20 grams/mole.
- Divide the mass of HF (5 grams) by the molar mass of HF (20 grams/mole).
5 grams / 20 grams/mole = 0.25 moles of HF.
Now, moving on to part (b):
b) Determine the molarity of HF using the moles of HF from question (a) and the volume of the solution assumed in (a).
- The molarity (M) is defined as moles of solute per liter of solution.
- In part (a), you assumed you have 100 milliliters (0.1 liters) of solution and found that you have 0.25 moles of HF.
- Divide the moles of HF (0.25 moles) by the volume of the solution in liters (0.1 liters) to find the molarity.
Molarity = Moles of solute / Volume of solution
= 0.25 moles / 0.1 liters
= 2.5 M
Therefore, the molarity of the HF solution is 2.5 M.