Lab 11 - acid-base titrations parts 1&2

Question 1

what are the safety considerations for potassium hydrogen phthalate (KHP)

Answer 1

toxicity from ingestion
(toxic if you eat or drink it)

Question 2

what are the safety considerations for sodium hydroxide 0.10 M

Answer 2

1. corrosive to skin (damages skin)
2. can cause serious eye damage
3. you must wear goggles at all times

Question 3

what are safety considerations for phenolphthalein indicator

Answer 3

• flammable liquid
• acute toxicity from ingestion (eat/drink it)

Question 4

what are safety considerations for hydrochloric acid (unknowns)

Answer 4

• corrosive to skin and mucous membranes
• can cause serious eye damage

Question 5

what is the objective of this lab?

Answer 5

• standardize a NaOH solution
• use the standard to determine the concentration of a HCl unknown

Question 6

KHP is a ____ for standardizing solutions of base
(high purity, large formula weight, water soluble)

Answer 6

1. KHP is a primary standard for standardizing solutions of base

Question 7

KHP reacts with NaOH in a 1:1 ____ ratio

Answer 7

KHP reacts with NaOH in a 1:1 stoichiometric ratio

HC8H4O4^-(aq) + OH^-(aq) —–) C8H4O4^2-(aq) + H2O(l)

Question 8

The HCl reacts with NaOH in a 1:1 ____ ratio.

Answer 8

The HCl reacts with NaOH in a 1:1 stoichiometric ratio.
HCl(aq) + NaOH(aq) → H2O(l) + NaCl(aq)

Question 9

The concentration of an ____ is most commonly determined by conducting a _____.

Answer 9

The concentration of an analyte is most commonly determined by conducting a titration.

Question 10

In a ____, a standard of known concentration is added in a controlled manner
to a specific volume of an unknown in order to determine the _____.

Answer 10

In a titration, a standard of known concentration is added in a controlled manner
to a specific volume of an unknown in order to determine the equivalence point.

Question 11

The ____ is reached when the number of moles of standard added equals the number of moles of unknown.

Answer 11

The equivalence point is reached when the number of moles of standard added equals the number of moles of unknown.

Question 12

For acid/base titrations, the ____ can be determined by using an _____

Answer 12

For acid/base titrations, the equivalence point can be determined by using an acid-base indicator

Question 13

An acid-base indicator changes ____ rapidly as the unknown solution goes from acidic to basic.

Answer 13

An acid-base indicator changes color rapidly as the unknown solution goes from acidic to basic.

Question 14

The point at which the indicator changes color is called the ______.

Answer 14

The point at which the indicator changes color is called the endpoint.

Question 15

The critical aspect of a titration is to selection an indicator so that the ____ and ____ occur simultaneously.

Answer 15

The critical aspect of a titration is to selection an indicator so that the endpoint and equivalence point occur simultaneously.