A 0.25 M CuSO4 solution is required. A student is given 60 grams of copper sulphate. Calculate the volume of water needed to dissolve copper sulphate crystals and make this solution.
M is one mole of solute per liter of solution
using the molar mass, calculate the moles of CuSO4
then calculate the liters of solution for 0.25 M
Your answer
For making a solution with predefined volume and concentration from a solid stock reagent (assuming 100% pure chemical), the formula ...
grams reagent needed = Molarity needed x Volume needed (Liters) x Formula Wt of reagent
So, for your problem ...
given 60 grams CuSO4 = 0.25 Molar solution x Volume needed (Liters) x 160 grams/mole CuSO4
Solve for Volume needed = 60g/[(0.25mole/L)(160g/mole)] = 0.150 L total volume solution = 150 ml total volume of solution...
Mixing should be as follows...
Transfer 60 grams CuSO4 into mixing container and follow with enough water to dilute to 150 ml... Now understand, that this method does Not say add 150 ml of water... It prompts one to add solvent (water) up to but not to exceed 150 ml total volume. The reagent will occupy some of the volume when dissolved.
To calculate the volume of water needed to dissolve copper sulfate crystals and make a 0.25 M solution, you first need to determine the number of moles of copper sulfate.
Step 1: Calculate the molar mass of copper sulfate (CuSO4):
- The atomic mass of Cu = 63.55 g/mol
- The atomic mass of S = 32.07 g/mol
- The atomic mass of O = 16.00 g/mol (4 oxygen atoms in CuSO4)
Molar mass of CuSO4 = (63.55 g/mol) + (32.07 g/mol) + (16.00 g/mol x 4) = 159.61 g/mol
Step 2: Convert the given mass of copper sulfate (60 grams) to moles:
- Moles = Mass / Molar mass
- Moles = 60 g / 159.61 g/mol ≈ 0.376 moles
Step 3: Determine the volume of solution needed:
- Molarity (M) = Moles / Volume (in liters)
- Rearranging the equation, Volume (in liters) = Moles / Molarity
- Volume (in liters) = 0.376 moles / 0.25 M = 1.504 liters
Therefore, you would need approximately 1.504 liters of water to dissolve 60 grams of copper sulfate and make a 0.25 M solution.