Add btb to the reaction and titrate with standardized

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- Add BTB to the reaction and titrate with standardized NaOH o Use same calibrated pipet o Took 17 drops Question 10: Show your calculations for the determination of the percentage of calcium carbonate in eggshells. Look back to experiment 3 to find the calibrated volume of the small drop pipet.
Penn State CHEM 111 6.78 * 10 -4 mol HCl * (1 mol CaCO 3 / 2 mol HCl) * (100 g CaCO 3 / 1 mol CaCO 3 ) = 0.03391 g CaCO 3 0.03391 g CaCO 3 / 0.0463 g eggshell = 0.7339 (*100) = 73.39% Question 11: We have obtained two other percentages of calcium carbonate values from previous experiments (see below). Calculate the average and standard deviation of these two values along with your calculated data from this worksheet. The standard deviation (s.d) should be rounded to 1 significant figure, and the final answer be expressed as the avg ± s.d. The average should be expressed to the correct number of sig figs based on the place of the reported s.d.
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70 ± 3 Question 12: Why not just do a “regular” titration? – i.e., what is the advantage of a back titration in this case?
Penn State CHEM 111 8 Section F: Acid Concentration in Fruits Pucker Order Please change the hypothesis in your Chemtrek to: There is a hypothesis that the pucker-promoting potential of fruits and fruit juices is directly proportional to the concentration of organic acids present in the fruit. Knowing that the order of sour taste, or pucker power, is Lemon > lime > grapefruit > orange for fruit juices, please use the information in the video to tell us whether you accept or reject the hypothesis. Pre-lab data collection and observations. Complete before lab. Read through this section in your Chemtrek and watch the video associated with this section. In the space below, summarize how the experiment was performed. Include any data and observations from the video in a table. Hypothesis: the pucker-power of fruit juice is directly related to the concentration of organic acid present in the fruit Juices least -> most - orange juice, grapefruit juice, lime juice, lemon juice Experiment - Large well titration on two drops of each juice all with BTB indication - Titrate with .1 M NaOH Observations - Each of the juices when leveled out with the NaOH turned blue - The more sour the more drops it took - There was a significant leap of the number of drops between grapefruit and Lime - They didn’t mix after each drop - They introduced the NaOH a lot faster juice orange grapefruit lime lemon Amount of drops 5 7 25 31 Question 9: (a) Report the concentration of acid in each of the fruit juices.

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