Acid-Base Titration

Acid-base titration is a laboratory procedure used to determine – among other things – the unknown concentration of an acid or a base.

Acid-Base Titration During an acid-base titration, an acidic solution of known concentration is added drop by drop to a base solution of unknown concentration (or vise versa) until all the hydrogen ions (H 1+ ) have exactly neutralized all the hydroxide ions (OH 1- ). OH 1- H 1+ HOH H 1+ HOH H 1+ HOH H 1+ HOH H 1+ HOH...when moles H 1+ equals moles OH 1-. An appropriate acid-base indicator will signal...

Acid-Base Titration During an acid-base titration, an acidic solution of known concentration is added drop by drop to a base solution of unknown concentration (or vise versa) until all the hydrogen ions (H 1+ ) have exactly neutralized all the hydroxide ions (OH 1- ). H 1+ HOH H 1+ HOH H 1+ HOH H 1+ HOH H 1+ HOH How many OH 1- ions were present in the original solution? Count the number of H 1+ ions added. H 1+ HOH six

Acid-Base Titration Remember, neutralization occurs when... the moles of H 1+ from the acid = the moles of OH 1- from the base The point of exact neutralization is called the equivalence point and is signaled by a color change (end point) in an acid-base indicator.

Acid-Base Titration 1) How many moles of NaOH does it take to neutralize 1.5 mol HCl? ________ 2) How many moles of LiOH does it take to neutralize 1.5 mol H 2 SO 4 ? ________ 3) How many moles of Ba(OH) 2 does it take to neutralize 1.5 moles of HNO 3 ? ________ 4) How many moles of Ca(OH) 2 does it take to neutralize 1.5 moles of H 2 CO 3 ? ________ OH H1.5 mol OH H2H2 3.0 mol (OH) 2 H0.75 mol (OH) 2 H2H2 1.5 mol

Acid-Base Titration Once the titration is complete, the concentration of the unknown solution is determined by employing the titration formula: M A V A = M B V B Beware: M A = molarity of H 1+ but V A = volume of the acid! M B = molarity of OH 1- but V B = volume of the base! this equation is tricky! MAMA H 1+ VAVA acid MBMB OH 1- VBVB base

Acid-Base Titration The molarity of H 1+ is equal to the acid’s molarity times the number of H 1+ ’s on the acid. M A = # H 1+ x M acid The molarity of OH 1- is equal to the base’s molarity times the number of OH 1- ’s on the base. M B = # OH 1- x M base

Acid-Base Titration 5) If the M A of an H 2 SO 4 solution is 2.0 M, then what is molarity (M) of the H 2 SO 4 solution? M A = # H 1+ x M acid (x) (2) 2.0 M = x = 1.0 M H 2 SO 4 1 H 2 SO 4 can produce 2 H 1+ ! M of H 1+

Acid-Base Titration 6) If the molarity (M) of an HNO 3 solution is 1.0 M, then what is the M A of the solution? M A = # H 1+ x M acid 1 HNO 3 can produce 1 H 1+ ! x = (1.0 M) (1) x = 1.0 M H 1+ M of H 1+

Acid-Base Titration 7) If the M A of an H 3 PO 4 solution is 1.2 M, then what is molarity (M) of the H 3 PO 4 solution? M A = # H 1+ x M acid 1 H 3 PO 4 can produce 3 H 1+ ! (x) (3) 1.2 M = 0.40 M H 3 PO 4 x = M of H 1+

Acid-Base Titration 8) If the molarity (M) of an Ba(OH) 2 solution is 0.25 M, then what is the M B of the solution? M B = # OH 1- x M base 1 Ba(OH) 2 can produce 2 OH 1- ! (0.25 M) (2) x = 0.50 M OH 1- M of OH 1-

Acid-Base Titration 9) If the M B of an Ca(OH) 2 solution is 1.0 M, then what is molarity (M) of the Ca(OH) 2 solution? M B = # OH 1- x M base 1 Ca(OH) 2 can produce 2 OH 1- ! (x) (2) 1.0 M = 0.50 M Ca(OH) 2 x = M of OH 1-

Acid-Base Titration 10)If the molarity (M) of an NaOH solution is 0.12 M, then what is the M B of the solution? M B = # OH 1- x M base 1 NaOH can produce 1 OH 1- ! (0.12 M) (1) x = 0.12 M OH 1- x = M of OH 1-

Acid-Base Titration 11)How many milliliters of a 1.50 M solution of H 2 SO 4 would exactly neutralize 7.50 mL of a M solution of Ba(OH) 2 ? M A V A = M B V B Choose an appropriate acid-base indicator. __________________ methyl orange or bromcresol green (7.50 mL) (0.500 M) (x) = (3.00 M) 1.25 mL x =

Acid-Base Titration 12)If 20.0 mL of an unknown solution of HCl is titrated with a 2.0 M solution of NaOH such that it required 37.0 mL of the NaOH to reach the end point, what is the molarity of the HCl? M A V A = M B V B Choose an appropriate acid-base indicator. __________________ (37.0 mL) (2.0 M) (20.0 mL) = (x) 3.7 M x = litmus or bromthymol blue of H 1+ The molarity of the HCl = 3.7 M

Acid-Base Titration 13)If mL of M H 2 CrO 4 solution is titrated against a 0.30 M NaOH solution, then how many milliliters of the base would be needed to reach the end point? M A V A = M B V B Choose an appropriate acid-base indicator. __________________ thymol blue or phenolphthalein (x) (0.30M) (150.0 mL) = (0.100 M) 50. mL x =

Acid-Base Titration 14)What is the molar concentration of a 25.0 mL sample of NH 3 (NH 4 OH) if it takes 8.0 mL of a 0.15 M solution of HBr to neutralize the NH 3 (NH 4 OH)? M A V A = M B V B Choose an appropriate acid-base indicator. __________________ methyl orange or bromcresol green (25.0 mL) (x) (8.0 mL) = (0.15 M) M x = of OH 1- The molarity of the NH 3 = M

Acid-Base Titration 15)How many milliliters of 0.10 M nitric acid (HNO 3 ) would be needed to neutralize 16.0 mL of a 0.15 M solution of Ba(OH) 2 ? M A V A = M B V B Choose an appropriate acid-base indicator. __________________ methyl orange or bromcresol green (16.0 mL) (0.30 M) (x) = (0.10 M) 48 mL x =

Acid-Base Titration 16)A student neutralized 16.4 milliliters of HCl by adding 12.7 milliliters of M KOH. What was the molarity of the HCl acid? M A V A = M B V B Choose an appropriate acid-base indicator. __________________ litmus or bromthymol blue (12.7 mL) (0.620 M) (16.4 mL) = (x) M x = of H 1+ The molarity of the HCl = M

17)What is the molarity of a solution containing 20.0 grams of NaOH in 500. milliliters of solution? x = __________ Acid-Base Titration 20.0 g 40.0 g/mol mol L M = mol L # mol = given mass GFM 1.00 M x = mol