Mass of gummy candy: 9.51 g

 

Chemical needed: 0.1M NaOH solution, sour gummy candy, pH indicator-phenolphthalein

 

Equipment: Graduated cylinder, weigh boat, scale, beakers, string rod, burette, conical flask, pH indicator, pipette, hot plate.

 

Procedure:

1. Put safety goggle on.
2. Put the weigh boat on a scale and use tear function to set the original weight to zero, take out gummy candy that contains tartaric acid, and put them on the weigh boat to get the mass of the gummy candy.
3. Measure 100 ml of water and put it into a beaker, put the candies into the beaker and dissolve by using the hot plate.
4. Set the hot plate to 100 Celsius degree and use the string rod to stir the solution to make it dissolve faster.
5. Once the solid part is fully dissolved, set up the titration station. Fill the burette with 0.1 M NaOH solution.
6. Measure 20 mL of the acid solution, pour the 20 mL solution into the conical flask and use a pipette to drop 5 drops of phenolphthalein into the solution.
7. Record initial volume of NaOH in the burette, and start dropping the NaOH solution. When the solution in the flask turns to light purple, stop dropping the NaOH and record the end volume, calculate the NaOH used.
8. Repeat step 6, 7 for 3 times and record the result.

 

 

 

Experiment #	Acid solution	NaOH solution used	Initial NaOH	End NaOH
1	20 mL	4.9 mL	0.9 mL	5.8 mL
2	20 mL	5.1 mL	5.8 mL	10.9 mL
3	20 mL	5.0 mL	10.9 mL	15.9 mL
4	20 mL	5.0 mL	15.9 mL	20.9 mL

Average NaOH used is = 5.0 mL

M1V1 = M2V2

 

[OH-] = 0.1 M · 0.005 L = M2 · 0.025L

M2 = 0.02 M

 

[H30+] = M1 · 0.02 L = 0.02 M · 0.025L

M1 = 0.025 M

 

pH = -log (0.025) = 1.6

Analysis: According to the pH scale, the pH of tartaric acid in the gummy candy is 1.6, a fairly strong acid.