Calculate the molar mass of a diprotic acid.
It reaches the endpoint of the titration with NaOH at 28ml.
The initial concentration of NaOH is 0.09792. and the initial mass of the diprotic acid is 0.685g. I keep getting a molar mass of 500g/mol. but the options are all around 100-150.
molesbase=1/2 moles acid
.028*.09792*1/2 .685/molmass
molmassacid= .685/(2* .028*.097920
I don't get anything near 500g/mol
So you need to times the molarity by two?
To calculate the molar mass of a diprotic acid, we first need to determine the number of moles of the acid used in the titration. We can then use this information along with the mass of the acid to calculate the molar mass.
From the given information, we know that the titration endpoint was reached at 28 mL of NaOH solution, which means that the moles of NaOH used in the reaction are equal to the moles of the diprotic acid.
Step 1: Calculate the moles of NaOH used in the reaction:
Moles of NaOH = concentration of NaOH × volume of NaOH
Moles of NaOH = 0.09792 M × (28 mL / 1000 mL/L)
Moles of NaOH = 0.00273856 mol
Step 2: Since the diprotic acid is diprotic, it will react with two moles of NaOH for every mole of acid. Therefore, the moles of the diprotic acid used in the reaction are half of the moles of the NaOH used.
Moles of Diprotic Acid = Moles of NaOH / 2
Moles of Diprotic Acid = 0.00273856 mol / 2
Moles of Diprotic Acid = 0.00136928 mol
Step 3: Now, let's calculate the molar mass of the diprotic acid.
Molar mass = Mass of Diprotic Acid / Moles of Diprotic Acid
Molar mass = 0.685 g / 0.00136928 mol
Molar mass = 499.997 g/mol
So, based on the given values, the calculated molar mass of the diprotic acid is approximately 500 g/mol. However, since you mentioned that the options provided are all around 100-150 g/mol, it is possible that there might be an error in your calculations or in the given values. Double-check the input values and re-calculate to ensure accuracy.