You want to prepare a standard potassium permanganate (KMnO4) solution of concentration 0,100 mol.dm cube .You have 3,95g of salt available.Determine which of these volumetric flask you should use 100ml,200ml,250ml or 500ml. Show all workings
To determine which volumetric flask to use, we first need to calculate the number of moles of potassium permanganate present in the given amount of salt.
The molar mass of potassium permanganate (KMnO4) is:
- Potassium (K) = 39.10 g/mol
- Manganese (Mn) = 54.94 g/mol
- Oxygen (O) = 16.00 g/mol (x4)
So the molar mass of KMnO4 is:
39.10 + 54.94 + (16.00 x 4) = 158.04 g/mol
Next, we can calculate the number of moles of KMnO4 using the following formula:
moles = mass / molar mass
moles = 3.95 g / 158.04 g/mol
moles = 0.025 mol
To prepare a solution with a concentration of 0.100 mol/dm^3, we multiply the desired concentration by the volume of the solution:
0.100 mol/dm^3 x volume (dm^3) = 0.025 mol
Rearranging the equation, we can solve for the volume in dm^3:
volume (dm^3) = 0.025 mol / 0.100 mol/dm^3
volume (dm^3) = 0.25 dm^3
The volume required is 0.25 dm^3. To convert it to ml, multiply by 1000:
volume (ml) = 0.25 dm^3 x 1000 = 250 ml
Therefore, you should use a volumetric flask with a capacity of 250 ml.
To determine the appropriate volumetric flask, we need to calculate the volume of the solution required.
Given:
Mass of KMnO4 = 3.95 g
Concentration of KMnO4 solution = 0.100 mol/dm³
Step 1: Calculate the molar mass of KMnO4
The molar mass of KMnO4 can be calculated by adding up the atomic masses of its constituent elements:
Molar mass of K = 39.10 g/mol
Molar mass of Mn = 54.94 g/mol
Molar mass of O = 16.00 g/mol (There are four O atoms in KMnO4)
Molar mass of KMnO4 = (39.10 g/mol) + (54.94 g/mol) + 4(16.00 g/mol)
Molar mass of KMnO4 = 39.10 g/mol + 54.94 g/mol + 64.00 g/mol
Molar mass of KMnO4 = 158.04 g/mol
Step 2: Calculate the number of moles of KMnO4
We can use the formula:
Number of moles (n) = mass (m) / molar mass (M)
Number of moles of KMnO4 = 3.95 g / 158.04 g/mol
Number of moles of KMnO4 = 0.025 mol
Step 3: Calculate the volume of the solution required
We can use the formula:
Volume (V) = Number of moles (n) / Concentration (C)
Volume of solution required = 0.025 mol / 0.100 mol/dm³
Volume of solution required = 0.25 dm³ (or 250 mL)
Therefore, you should use the 250 mL volumetric flask to prepare the standard KMnO4 solution of concentration 0.100 mol/dm³.