calculate the normality of 5.56 grams of K2Cr2O7 dissolved in 500 mL
To calculate the normality of a solution, you need to know the number of moles of the solute and the volume of the solution. Here's how you can calculate it step-by-step:
1. Determine the number of moles of K2Cr2O7:
- The molar mass of K2Cr2O7 can be calculated by adding up the individual atomic masses of its elements. In this case, it is:
Molar mass of K2Cr2O7 = 2(atomic mass of K) + 2(atomic mass of Cr) + 7(atomic mass of O)
= 2(39.10 g/mol) + 2(52.00 g/mol) + 7(16.00 g/mol)
= 294.18 g/mol
- Now, we can calculate the number of moles of K2Cr2O7:
Number of moles = mass / molar mass
= 5.56 g / 294.18 g/mol
≈ 0.0189 mol
2. Convert the volume to liters:
- The volume of the solution is given as 500 mL. To use it in the normality calculation, we need to convert it to liters by dividing by 1000:
Volume = 500 mL / 1000 mL/L
= 0.500 L
3. Calculate the normality:
- Normality is the number of equivalents of solute per liter of solution. In this case, K2Cr2O7 is a strong acid dissociating into three ions, so each mole contributes six equivalents.
Normality = (Number of moles of solute * Number of equivalents per mole) / Volume of solution
= (0.0189 mol * 6 equivalents/mol) / 0.500 L
= 0.2268 equivalents / 0.500 L
≈ 0.454 M
Therefore, the normality of the solution is approximately 0.454 N.