ferrous sulfate was prepared by dissolution of x grams p feso4.7H20 crystals in 500 ml water. 20 ml of this solution necessities 5 ml of 0.1mol/l kmn04 for the pink color to persist. find x
You may wish to balance the ENTIRE equation but I'll leave that to you. I'll balance just the part that matters.
5Fe*2+ + MnO4^- ==> Mn^2+ + 5Fe^3+
mols KMnO4 = M x L = ? mols in the 20 mL sample. How many mols KMnO4 will that be in the 500 mL sample? That's ?mols in 20 mL x (500/20) = ? and that's the mols FeSO4.7H2O in the original sample of x grams.
Convert mols FeSO4.7H2O to grams.
grams = mols x molar mass = ?
To find the value of "x," we need to solve this problem step by step. Here's how you can approach it:
1. Understand the given information:
- The solution is prepared by dissolving "x" grams of FeSO4.7H2O crystals in 500 ml of water.
- It is mentioned that 20 ml of this solution is needed for the subsequent step.
2. Identify the reaction taking place:
From the given information, we can deduce that the reaction involves the oxidation of Fe2+ (from FeSO4) to Fe3+ by KMnO4. The complete balanced equation for this reaction is:
8H+ + 5Fe2+ + MnO4- -> 5Fe3+ + Mn2+ + 4H2O
3. Determine the stoichiometry of the reaction:
From the balanced equation, we can observe that 5 moles of Fe2+ react with 1 mole of KMnO4.
4. Calculate the number of moles of KMnO4 used:
Given that 5 ml of 0.1 mol/L KMnO4 is used, we can calculate the number of moles of KMnO4 used using the formula:
Moles = Concentration (mol/L) * Volume (L)
Moles of KMnO4 = 0.1 mol/L * 0.005 L (since 5 ml is converted to liters by dividing by 1000)
Moles of KMnO4 = 0.0005 mol
5. Determine the number of moles of Fe2+ reacted:
From stoichiometry, we know that 1 mole of KMnO4 reacts with 5 moles of Fe2+. Therefore, the number of moles of Fe2+ reacted can be calculated using the ratio:
Moles of Fe2+ = (0.0005 mol of KMnO4) * (5 mol of Fe2+ / 1 mol of KMnO4)
Moles of Fe2+ = 0.0025 mol
6. Calculate the molar mass of FeSO4.7H2O:
The molar mass of FeSO4 is 151.91 g/mol, and there are 7 H2O molecules associated with each FeSO4 molecule. Therefore:
Molar mass of FeSO4.7H2O = (151.91 g/mol) + (7 * 18.02 g/mol)
Molar mass of FeSO4.7H2O = 278.94 g/mol
7. Determine the mass of FeSO4.7H2O used:
Mass of FeSO4.7H2O = (Moles of Fe2+) * (Molar mass of FeSO4.7H2O)
Mass of FeSO4.7H2O = (0.0025 mol) * (278.94 g/mol)
Mass of FeSO4.7H2O = 0.69735 g
So, x is equal to 0.69735 grams or approximately 0.697 grams.