I'm having a lot of trouble with a simple problem. I have a 3.0% by man solution of H2O2 in H2O. The density of thr solution is 1.0 g/mL. I need to find the molarity. How do I do this? So far I have:
3.0g H2O2 x 1 mol/34.02 g= .0881 mol
I'm not sure where to go or what to do with density, though.
Assume 100 grams of solution.That means three grams of peroxide, and ninety-seven of water.
Molarity= molesH2O2/volume solution
using the density, the volume is 100ml
To find the molarity (M) of the solution, you need to know the moles of solute (H2O2) and the volume of the solution.
You correctly calculated the moles of H2O2. The molar mass of H2O2 is 34.02 g/mol, so 3.0 g H2O2 is equal to 0.0881 mol H2O2.
Now, you need to find the volume of the solution. Given that the density of the solution is 1.0 g/mL and assuming a total mass of 100 grams, you can calculate the volume using the given density:
Volume = mass / density
Volume = 100 g / 1.0 g/mL
Volume = 100 mL
Now that you have the moles of H2O2 (0.0881 mol) and the volume of the solution (100 mL), you can calculate the molarity using the formula:
Molarity = moles of solute / volume of solution
Molarity = 0.0881 mol / 100 mL
However, to express the molarity in a more commonly used unit, you need to convert the milliliters (mL) to liters (L). There are 1000 mL in 1 L, so the volume in liters is:
Volume = 100 mL / 1000 mL/L
Volume = 0.100 L
Now, plug in the values to calculate the molarity:
Molarity = 0.0881 mol / 0.100 L
Molarity = 0.881 M
Therefore, the molarity of the 3.0% H2O2 solution is 0.881 M.