I\'ve given you a procedure on my titration lab along with the two tables I need

Question

I've given you a procedure on my titration lab along with the two tables I need to fill out. (have not performed lab yet)

Obviously, I don't expect you to do the lab. I just need some help with some parts of the data table.

On Part A Data Table, I need help with what formula to use to find molarity of NaOH. I know its moles of solute/L. The volume is obvious to me. I am just having struggles determining the moles.

On Part B Data Table, I am not fully grasping how to get the two bottom boxes (g, absorbic acid) and (% absorbic acid in sample)

Any information/formulas you can help me when performing this lab will be great. FYI my main struggles are with the boxes on Part B.

Thank you for your time.

Experiment 8 Protected View - Saved to this PC Sign in File Home Insert Design LayoutReferences Mailings ReviewView Help Tell me what you want to do V. Procedure Part A-Standardization of NaOH An acid-base titration requires the use of a standardized (known concentration) solution of sodium hydroxide and an indicator such as phenolphthalein, which is colorless in an acid but deep mauve in a basic solution. I is impossible to accurately weigh solid sodium hydroxide because it absorbs moisture and carbon dioxide from the air. The required volume of a solution of the approximate concentration needed is prepared. A more accurate concentration is found by titrating a known mass of a solid acid, such as oxalic acid dihydrate, (?.?,042H,O) with the solution 1. Mass three samples of oxalic acid dihydrate, about 0.1 g each. Record the mass to 0.001 g 2. Place each sample in a numbered 250-mL conical flask. Add about 75 mL distilled water and 4 drops of the indicator, phenolphthalein solution to each flask. Swirl the flask to dissolve e the crystals completely. No solid should remain at the end of the titration. 3. Fill the burette with 0.1 MNaOH and titrate all the three samples of oxalic acid. Be sure to record the initial and final readings. After the data is collected, calculate the molarity of the NaOH solution using the proper number of significant figures. 4. Part B. Determination of Ascorbic Acid by Acid-Base Titration The procedure for titrating ascorbic acid is very similar to that used for standardizing the base. However, now the concentration of the base is known, but the quantity of ascorbic acid in the tablet is not. 1. Refill to 0.00 mL (or the nearest whole number line) the burette containing the standardized NaOH solution. 2. Obtain two 500 mg Vitamin C tablets, record total mass to three decimal places, and crush in a mortar and pestle. Obtain and number three 250 mL Erlenmeyer flasks. Add to each a sample of the powder with a mass of about 0.300 g, very carefully weighed out, recorded, and transferred. Add 50-60 mL of deionized water to each and swirl to dissolve. The tablets include insoluble filler, so a finely divided solid will remain. 3. Add 3-5 drops of phenolphthalein indicator to each and titrate to the first permanent pale pink endpoint, recording each volume measurement. Page 3 of 7 1068 words 95% O Type here to search 3:46 PM 4/14/2018

Explanation / Answer

Part A)

standardization of NaOH

(COOH)2 + 2NaOH --> (COONa)2 + 2H2O

moles of oxalic acid = mass oxalic acid/molar mass oxalic acid

moles NaOH = 2 x moles oxalic acid

molarity NaOH = moles NaOH/volume of NaOH added

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Part B)

Determination of ascorbic acid

1 mole ascorbic acid reacts with 1 mole NaOH

moles NaOH = molarity of NaOH x volume NaOH added

moles ascorbic acid = moles NaOH

mass ascorbic acid in sample = moles ascorbic acid x molar mass ascorbic acid

%ascorbic acid in sample = mass ascorbic acid x 100/mass tablet

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