Answer:
[tex]\boxed {\boxed {\sf 0.687 \ M}}[/tex]
Explanation:
We are asked to find the unknown concentration of the acid given the details of a titration experiment.
A formula for titration is:
[tex]M_AV_a= M_BV_B[/tex]
where M is the molarity of the acid of base and V is the volume of the acid or base. There are 56.0 milliliters of the acid (H₃PO₄), but the concentration or molarity of the acid is unknown. There are 88.2 milliliters of the base (KOH) with a molarity of 0.436.
[tex]\bullet \ V_A= 56.0 \ mL\\\bullet \ M_B= 0.436 \ M \\\bullet \ V_B= 88.2 \ mL[/tex]
Substitute the values into the formula.
[tex]M_A * 56.0 \ mL = 0.436 \ M * 88.2 \ mL[/tex]
We are solving for the molarity of the acid, so we must isolate the variable [tex]M_A[/tex]
It is being multiplied by 56.0 milliliters and the inverse operation of multiplication is division. Divide both sides of the equation by 56.0 mL.
[tex]\frac {M_A * 56.0 \ mL}{56.0 \ mL} = \frac{0.436 \ M * 88.2 \ mL}{56.0 \ mL}[/tex]
[tex]M_A = \frac{0.436 \ M * 88.2 \ mL}{56.0 \ mL}[/tex]
The units of milliliters/mL cancel.
[tex]M_A = \frac{0.436 \ M * 88.2 }{56.0 }[/tex]
[tex]M_A = \frac{38.4552 }{56.0} \ M[/tex]
[tex]M_A = 0.6867 \ M[/tex]
All the original measurements have 3 significant figures, so our answer must have the same. For the number we calculated, that is the thousandths place. The 7 in the ten-thousandths place tells us to round the 6 up to a 7.
[tex]M_A= 0.687 \ M[/tex]
The molarity of the acid is 0.687 M.
