A 75.0g sample of liquid contains 17.5% by mass of H3PO4 (molar mass = 98.0g/mol). If
215.0mL of Ba(OH)2 is needed to completely neutralize the acid, determine the concentration
of the Ba(OH)2 solution used. WITH FULL EXPLANATION PLEASE!
a. determine moles of acid
75*.175/98
Heq*molesacid=Heqbase*Molaritybase*.215
3*75*.175/98=2*M*.215
solve for molarity of the base.
To find the concentration of the Ba(OH)2 solution used, we need to first determine the number of moles of H3PO4 in the sample solution, and then use the stoichiometry of the reaction between H3PO4 and Ba(OH)2 to find the number of moles of Ba(OH)2 used. Finally, we can calculate the concentration of the Ba(OH)2 solution.
Let's go step by step:
Step 1: Calculate the number of moles of H3PO4 in the sample solution.
Given:
Mass of liquid sample = 75.0g
Percent by mass of H3PO4 = 17.5%
We can calculate the mass of H3PO4 in the sample solution:
Mass of H3PO4 = (17.5/100) * 75.0g = 13.125g
Now, we can calculate the number of moles of H3PO4:
Number of moles of H3PO4 = Mass of H3PO4 / Molar mass of H3PO4
Molar mass of H3PO4 = 98.0g/mol
Number of moles of H3PO4 = 13.125g / 98.0g/mol
Step 2: Determine the number of moles of Ba(OH)2 used.
From the balanced chemical equation between H3PO4 and Ba(OH)2:
H3PO4 + 3Ba(OH)2 → Ba3(PO4)2 + 6H2O
We can see that for every 1 mole of H3PO4, we need 3 moles of Ba(OH)2. Therefore, the number of moles of Ba(OH)2 used will be 3 times the number of moles of H3PO4.
Number of moles of Ba(OH)2 = 3 * Number of moles of H3PO4
Step 3: Calculate the concentration of the Ba(OH)2 solution.
Given:
Volume of Ba(OH)2 solution used = 215.0mL
First, convert the volume of the solution from milliliters to liters:
Volume of Ba(OH)2 solution used = 215.0mL = 215.0mL * (1L/1000mL) = 0.215L
Now, we can calculate the concentration (Molarity) of the Ba(OH)2 solution:
Concentration of Ba(OH)2 = Number of moles of Ba(OH)2 / Volume of Ba(OH)2 solution used
Substituting the values we have:
Concentration of Ba(OH)2 = (3 * Number of moles of H3PO4) / Volume of Ba(OH)2 solution used
Now you can substitute the calculated values into the equation and solve for the concentration of Ba(OH)2.