Use Figure 19.6 to find an indicator for these titrations: (a) 0.5M(CH3)2 NH( Appendix C) with

Use Figure 19.6 to find an indicator for these titrations:...

Key Concepts

Titration Types (Weak Base-Strong Acid and Strong Acid-Strong Base)

Different titration types exhibit distinct titration curves, particularly in terms of the pH at the equivalence point. In a weak base-strong acid titration, the equivalence point typically falls in the acidic range due to the formation and subsequent hydrolysis of the conjugate acid. Conversely, a strong acid-strong base titration results in an equivalence point that is close to neutral pH, as the resulting salt does not hydrolyze significantly. Understanding these differences is key to selecting an appropriate indicator.

pH Transition Range

The pH transition range of an indicator is the interval over which the indicator changes color. In titration, it is important that this range encompasses the pH of the equivalence point, so that the change in color can accurately indicate that the titration has reached its endpoint. This concept is especially significant when choosing indicators for titrations that have equivalence points in non-neutral pH regions.

Equivalence Point

The equivalence point in a titration is the stage at which the quantity of titrant added is exactly sufficient to completely neutralize the analyte present in the solution. The pH at the equivalence point depends on the strength of the acid and base involved; for instance, titrations involving a weak base with a strong acid typically have an equivalence point pH below 7, while titrations between a strong acid and a strong base reach an equivalence point around pH 7.

Acid-Base Titration

Acid-base titration is a quantitative analysis technique that involves the gradual addition of a titrant (an acid or a base) to a solution containing an analyte (a base or acid, respectively) until the reaction reaches its neutralization endpoint. This process allows for the determination of the analyte's concentration by measuring the volume of titrant required to reach the equivalence point.

Indicator Selection

Indicator selection is crucial because the indicator must change color at a pH close to the equivalence point to accurately signal the completion of the reaction. This requires matching the indicator’s transition range to the expected pH change during the titration, ensuring that the color change occurs at or near the actual equivalence point.

Transcript

00:03 In this problem, we are asked to find the indicators of the following titrations.

00:10 In part a, we know that this is a titration between a weak base and a strong acid.

00:18 And in a titration between a weak base and a strong acid, the equivalence point will have a ph that is greater than 7.

00:28 We will need to construct an ice table.

00:31 We will first write out our chemical equation for this reaction.

00:41 Since both the base and acid are solutions in one liter, our number of moles would be 0 .5 moles for both the base and the acid.

01:01 So this is where we will start off.

01:04 And at the equivalence point the number of moles for the acid and the number of moles for the base should be equal to each other next we will minus both sides by 0 .5 moles because this is the number of moles that will go under reaction and we will find our final number of moles for this reaction next we will need to find the molarity of ch3 and h2.

01:46 Now because for the base and acid, they both are constituted of 1 liter.

01:55 So in addition, or the sum of the acid and the base will give us 2 liters.

02:01 So to solve for the malarity, we will have 0 .5 moles over 2 liters, which gives us 0 .25 molars.

02:16 Next, we will do another ice table for the strong acid.

02:29 In this, we will solve for the concentration of h -30 plus to solve for our ph value, which will help us indicate what our indicator is...

Please give Ace some feedback