Larkin Lab Report- Titration

7/28/2019 Larkin Lab Report- Titration

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Cristian Rodriguez

May 13, 2013

Period 4

Whos the One to Blame?

Introduction:

A titration is a lab technique used to determine the exact concentration of an

unknown acid or base. Often times, acids and bases are identified based on their physical

properties. An acid is a typically sour substance that gives away their hydrogen ions

when dissolved in water with a base and turns litmus paper red. The characteristics of a

base are the opposite of an acid. They absorb hydrogen ions and turn litmus paper blue

The purpose of this lab is to identify who killed Mr. M by analyzing and matching the

Molarity of the Crime Scene HCl acid sample to the Molarity of the suspects found in the

investigation. In this lab, the acid samples will behave as the solvents of the solution or

the substance that takes up most of the volume and the bases will behave as solutes or

substances that take up less volume when both are blended. The result of this mixture

should be a neutralization reaction, a reaction in which an acid and a base in an aqueous

solution react to produce neutral water and salt. In addition, after the experiment, it will

be necessary to identify the Molarity of HCl by using the formula (moles/ liters) in order

to compare the different Molarity to find the killer.

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Procedures:

1. Before starting, the students wore their goggles on and obtained the following

materials:

A 50 ml graduated cylinder

A 50 ml burette, stand, and cylinder

A 125ml Erlenmeyer flask Phenolphthalein indicator

Glass funnel

2. The stopcock was turned towards the bottom and remained perpendicular to

the tube of the burette in a closed position.3. The burette was filled with 1.0 M NaOH base. Then the initial volume was

recorded.

4. The graduated cylinder was utilized to measure 20ml exactly for each acid

sample.5. 3 drops of phenolphthalein indicator were added to the acid samples ( the acid

remained clear).6. The stopcock was opened until there was a slow stream of NaOH in order to

titrate the unknown acid.

7. When the drops fell, the flask was swirled and the coloring disappeared.

Observations were recorded in the results section.8. When a solution was approaching neutralization, it became piker more rapidly

and will later clear itself.

9. Then, the stopcock was gently, partially opened and little drops were pouredinto the acid sample.

10. When the coloring did not disappeared, the stopcock was quickly closed. If

the solution had a very faint pink color, then it was a good titration. Though, if

the titration was dark pink, it was necessary to redo the proceadures over intrial 2.

11. The Final Volume of NaOH in the burette was recorded.

12. The Total Volume (in mL) of NaOH was calculated. It neutralized thesuspects sample and the data was recorded.

13. The burette was refilled with NaOH and the procedures were repeated with

the other 3 samples.

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Data:

(Table 1): Data for in search of the Final Volume of NaOH

Exact

Volume of

HCl (mL)

Initial

Volume of

NaOH(mL)

Final

Volume of

NaOH(mL)

Total

Volume of

NaOHUsed in

titration(mL)

Molarity

of HCl

(M)

Observatio

/ Notes

Suspect A

Kirkpatrick

HCl Acid

Trial

1

20mL 10mL 20mL 10mL .5M. -dark pink

Trial

2

20mL 20.5mL 30mL 9.5mL -light pink

Suspect B

Larkin

HCl

Acid

Trial

1

20mL 3mL 8.5mL 5.5mL -dark pink

Trial

2

20mL 8.5mL 13mL 4.5mL .225M -light pink

Suspect C

Nguyen

HCl Acid

Trial

1

20mL 13mL 27mL 14mL .7M -light pink

Trial

2

20mL 27mL 43mL 14mL -light pink

Crime Scene

HCl Acid

Trial

1

20mL 1mL 5.5mL 4.5mL -dark pink

Trial

2

20mL 5.5mL 9.5mL 4mL .2M -light pink

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Calculation Table 2:

Acid Sample 1. Moles of NaOH 2. Moles of HCl 3. Molarity of HCl

(moles HCl/Liters HCl

used)

Suspect AMrs.Kirkpatrick

.01 mol 0.1 mol HCl0.5 mol HCl

Suspect B

Mr. Larkin

.0045 mol .0045 mol HCl

0.23 mol HCl

Suspect C

Ms.Nguyen

.014 mol .014 mol HCl 0.7 mol HCl

Crime Scene

Sample

.004 mol .004 mol HCl 0.2 mol HCl

Conclusion:

At the end of the titration lab, it was concluded that Mr. Larkin is responsible for

Mr. Mehkatarians death. The acid samples, the solvents of the solution, were mixed with

drops of phenolphthalein and NaOH, both solutes, created a homogenous reaction. For

example, the acid sample for Mrs. Kirkpatrick was mixed with both the phenolphthalein

indicator and with NaOH, and turned the acid sample into a dark pink for the first trial

and a light pink for the second trial. This indicates when the solution is light pink, it is a

weak, less concentrates acid. However, if the acid was dark pink after the solvents were

poured into it, then acid was strong thus more concentrated. After the experiment, the

Moles HCl were found. But first, the equation was balanced forNaOH + HCL and

obtained NaCl + H2O. The balanced equation demonstrates that an acid donates its

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Hydrogen ions to the base when both are dissolved in water. When the moles of HCl

were found and its Molarity, the Molarity of each acid sample, including the crime scene

were compared in order determine the rue killer. In the end, the concentration of the acid

sample of Mr. Larkin was similar to the sample found in the crime scene, indicating that

Mr. Larkin was found guilty.

Although the results and data were obtained, there were sources of error present

as well. One source of error that affected the data was the testing materials such as the

Erlenmeyer flask. The materials were not fully cleaned and perhaps the actual amount of

NaOH needed when added to the HCl is inaccurate. As a result, multiple trials were

performed for each acid sample, making trial 1 for each acid sample unreliable. Another

source of error was the stand because it was loose. When NaOH was poured into the acid

sample, the students had to read the scale of the 50mL burette; however, the burette was

difficult to read because it was slanted. As a result, the column for the Final Volume of

NaOH is unreliable. If the materials were fully rinsed before the experiment and if the

stand was not slanting, the data could have been more accurate.

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Larkin Lab Report- Titration

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