16.4 : Titrations EQUIVALENCE POINT: the point in the titration when the # of moles of acid is stoichiometrically equal to the # of moles of base. Titration of a strong substance with a strong substance generates a pH of 7.00 at equivalence point. TITRATION OF A STRONG ACID W/ A STRONG BASE PROBLEM: Calculations: 1. Find the Volume of Base needed to reach equivalence pointstep 1: go from mL to L to moles of acid (this is also = to the moles of base because at equivalence point they are equal) step 2: use the concentration of the base to go from moles to L (vol.)2. Find initial pH of the solution before titrationstep1: this is before the base is added so the only thing present is the acid and water. Since this is a strong acid, the concentration of the acid is also the concentration of H3O+. step 2: plug that concentration into pH= -log(H3O+) to get pH3. Find pH before equivalence pointstep 1: go from mL of added base to L of added base to moles of added base. step 2: do a “before/add/after” chart to calculate the amount of acid that isleft in moles. step 3: convert acid from moles to M, which is equal to the amount of H3O+ ions and then you can get pH. 4. pH at equivalence point* this is always 7.00 5. Find the pH after equivalence pointstep 1: go from mL to L to moles of added base. Then subtract the number of moles of base required to reach equivalence point. This will give you the amount of leftover base in moles that effects pH.step 2: divide the leftover moles of base by the total L of solution to find the concentration of the base (M). Since it is a strong base that also equals the amount of OH- ions. From here you can take the –log(OH) to find pOH. Then do 14-pOH= pH TITRATION OF A WEAK ACID W/ A STRONG BASE PROBLEM: Calculations: 1. Find the Volume of Base needed to reach equivalence pointstep 1: go from mL to L to moles of acid (this is also = to the moles of base because at equivalence point they are equal) step 2: use the concentration of the base to go from moles to L (vol.)2. Find initial pH of the solution before titrationstep1: this is before the base is added so the only thing present is the acid and water. Since this is a weak acid, use an ice table to find the concentration of H3O+. step 2: plug that concentration into pH= -log(H3O+) to get pH.3. Find pH before equivalence pointstep 1: go from mL of added base to L of added base to moles of added base. step 2: do a “before/add/after” chart to calculate the amount of acid that isleft and the amount of conjugate base that has been produced in moles step 3: use the Henderson-Hasslebalch equation to get pH. 4. pH at equivalence pointstep 1: go from mL of added base to L of added base to moles of added base. step 2: do a “before/add/after” chart to calculate the amount of conjugate base that has been produced in moles (since products are the only thing left in the solution that hasn’t reacted). Then find the concentration (M) of the conj. Base. step 3: make a new equation with the conj. Base + water the original acid and OH-. Then do an ice chart to find the concentration of OHstep 4: find pOH, then 14-pOH =pH 5. Find the pH after equivalence pointstep 1: go from mL to L to moles of added base. Then subtract the number of moles of base required to reach equivalence point. This will give you the amount of leftover base in moles that effects pH.step 2: divide the leftover moles of base by the total L of solution to find the concentration of the base (M). Since it is a strong base that also equals the amount of OH- ions. From here you can take the –log(OH) to find pOH. Then do 14-pOH=
View Full Document
Unlocking...