Acid and Base Titrations Lab Report PDF

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Acid and Base Titrations Lab Report CHM 114 JX 9-25-2016

Abstract This experiment’s goal was to give us experience finding the standardization of through the use of a primary standard. In this experiment we will be using NaOH and HCL as well as KHP. In

order to do this we will be titrating a known molarity of NaOH into KHP with an indicator and doing twice. The same procedure will be done for HCL. Save the HCl and NaOH solutions that are used as they will be needed next week. The reaction we used was: HCl(aq) + NaOH(aq) ----> NaCl(aq) + H2O(l)

Procedure 1. Pour 16.67mL of 3M NaOH into 500 mL of DI water and mix well. 2. Clean and label two 250 mL Erlenmeyer flasks as “sample 1” and “sample 2”. Weigh out approx 0.4-0.5 grams of KHP in a weigh boat twice and record the weights. Then pour all of the KHP into sample 1 and sample 2. 3. Rinse and clean buret with 3 or 4 mL of NaOH solution and then fill with same substance to above the 0 mark. Use a waste beaker to catch the substance while it is coming out of the buret to allow the tip of the buret to be filled with liquid and remove bubbles. Adjust liquid level to a value between 0.00 and 2.00 mL. Record value into manual. 4. Add 50 mL of DI water to both 250 mL flasks. Add 3 or 4 drops of 0.1% phenolphthalein indicator solution and begin titration for sample 1. Slowly titrate the substance an swirl the flask to make sure it is dispersed evenly. Keep going until it becomes a light pink. Record how much mL it took to reach this point. Repeat this for sample 2. 5. Pour standardized solution of NaOH into a labeled bottle after rising it a few times (3-5) with 5 mL of NaOH 6. Empty and clean everything except for buret. 7. Pour 16.67 mL of 3M HCL into 500 mL of DI water. 8. Turn NaOH buret to the side and obtain a new buret to fill and rinse with HCl solution as done in step 3. However fill to the 40 mL mark with the HCl solution and record the point it is at. 9. Add ~35 mL of HCl from the buret to the flasks. Refill buret inbetween to 40 mL if needed. 10. Refill NaOH buret to 45 mL and record initial value and then begin titration of NaOH into HCl for sample 1. 11. Slowly swirl the sample while titrating to evenly disperse the NaOH. Titrate until a light pink and then record the value of how much mL of NaOH it took. Repeat the titration steps for sample 2. 12. Pour HCl solution into a 500 mL bottle and label it with the molarity and substance inside.

Data 1. NaOH

Sample:

1

2

Wt. KHP

0.4637g

0.4306g

Mmol of KHP

(0.4647/204.2)x1000 = 2.27

(0.4306/204.2)x1000 = 2.11

Final Buret reading

24.72

22.75

Initial Buret reading

0.52

0.53

Volume of NaOH used

24.2

22.22

Molarity:

0.094

0.095

Avg. Molarity: (0.094 + 0.095)/2 = 0.0945 Molarity found using M base= (g KHP x 10^3)/[(ml of Base)(mw KHP) 2. HCL Sample

1

2

Final Buret reading

45.02

45.05

Initial Buret reading

10.01

10.02

Volume of HCL in Flask

35.01

35.03

NaOH Final Buret reading

39.95

40.18

NaOH Initial Buret reading

5.02

4.95

Volume of NaOH used

34.93

35.23

Molarity of HCl

0.094

0.095

Avg. Molarity: (0.094 + 0.095)/2 = 0.0945 Molarity of HCl Found via M1V1=M2V2 solving for M1

Calculations Molarity of KHP: M base= (g KHP x 10^3)/[(ml of Base)(mw KHP) M base = (0.4647 x 10^3)/[(24.21 ml)(204.2g)] = 0.094 M base = (0.4306 x 10^3)/[(22.22 ml)(204.2g)] = 0.095 Molarity of HCl Found via M1V1=M2V2 solving for M1 (34.93)(0.0945)=(35.01)(M) -> [(34.93)(0.0945)]/35.01=(M) = 0.094 (35.03)(0.0945)=(35.01)(M) -> [(34.93)(0.0945)]/35.01=(M) = 0.094

Discussion of Results Based off the results in the calculations I found both of the Molarity values were the same for

HCl and NaOH which was expected as they both underwent the same exact procedure and were at a 1 to 1 M ratio to each other.

Conclusions The purpose of this lab was to give us experience titrating and standardizing bases and acids. We were able to learn how to use an indicator to show us where the equivalence point was. We also learned how to calculate M of base with the formula used in the calculations for M of NaOH. We couldn’t account for the atmosphere in the lab so this led to suboptimal conditions. We could solve this by using a controlled environment for the experiment to take place in to avoid losing any KHP. We could have also redone the experiment multiple times to get more accurate results. The experiment would need to be repeated to test accuracy of results....