I need help with #3. That’s how far I’ve gotten so far and I’m stuck. Help pleas

Question

I need help with #3. That’s how far I’ve gotten so far and I’m stuck. Help please e-lab calculations: (remember ascorbic acid is a weak acid). Calculate the masses of sodium phos p the pH constant during this experiment dibasic (Na2HPOs) and sodium phosphate monobasic monohydrate (NaH2PO. H20) needed to prepare 100.0 mL of 0.1000 M buffer with a pH of 7.0 2. Calculate the volume of 0.01000 M Ks[Fe(CN)o] you will need to prepare 100.0 mL of a 0.50 mM solution. 3. Calculate the mass of ascorbic acid needed to prepare 10.00 mL of a 0.060 M solution ow each of these calculations in your laboratory notebook. Watch your significant figures ar its. (You will be using volumetric flasks to make all of the solutions.) ocedure tassium Ferricyanide Preparation Prepare 100 mL of your phosphate buffer by adding the appropriate amounts of the sodiur ono and dibasic phosphates in a 100 mL volumetric flask. Add DI H20 below the calibration ark. Transfer to a beaker and check the pH. Add strong base or acid dropwise to adjust the to 7. Transfer back to the volumetric flask and adjust volume to the mark. Pipet the appropriate volume of 0.01000 M Ks[Fe(CN)s] to another 100 mL volumetric flas make 0.50 mM Ks[Fe(CN)s] solution. Dilute to the mark using your phosphate buffer solutio Add approximately 30 mL of this 0.50 mM KslFe(CN)o] solution to a 50 mL beaker. Add a r and place on stir plate Place the ORP sensor (this contains a Ag/AgCI reference electrode and a platinum working ectrode) into the solution. Make sure that the stir bar is not hitting the ORP sensor. The OR nsor can be plugged into a channel of the LabQuest. Calibrate a LabQuest spectrometer and set to 420 nm Record the initial absorbance of ferricyanide. To measure the absorbance, remove some c e solution from the beaker with a beral pipet and fill a cuvette. Use the spectrometer to asure the absorbance. Return the cuvette solution back to the beaker. Do not rinse cuvett corbic Acid Preparation Prepare 0.060 M ascorbic acid in a 10 mL volumetric flask Pour into a small beaker 060 M ascorbic acid to the stirri

Explanation / Answer

3.

Moles of ascorbic acid = Molarity of ascorbic acid * volume of solution in L

n = 0.060 * 10.00 / 1000

n = 0.00060 mol

But,

Number of moles = mass / molar mass

Therfore, Mass of ascorbic acid = 0.00060 * 176.1

mass of ascorbic acid = 0.106 g.

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