May you please show steps on how you prepare each stock solution. Thank you Samp

Question

May you please show steps on how you prepare each stock solution. Thank you

Sample Preparation for Titration Experiment (pH Dependence of H Chemical Shift Preparation of Stock HCl and KOH Solutions: 1. Work in the fume hood! To prepare 4 mL of 1.0 M stock HCl solution, dilute 37% (w/w) HCI (MW = 36.46 g/mol, d = 1.18 g/mL at 25°C) with 10% D20 (i.e., 90% H2O) stock solution. Remember to add acid to water as the reaction is highly exothermic. 2. To prepare 4 mL of 1.0 M KOH stock solution, measure the mass of two KOH pellets (MW = 56.11 g/mol). Calculate the volume of 10% DO required and dissolve the pellets with 10% D20 stock solution. Make sure the pellet is completely dissolved. Properly label each solution.

Explanation / Answer

1) for 4mL of 1 M HCl solution

The moles of HCl needed = Molarity X volume (L) = 1 X 4 / 1000 = 0.004 moles

so these moles are needed in total 4mL of solution Or 0.004 X 36.5 grams = 0.146grams

the concentration of Hcl = 37w/w%

So it means 37grams in 100g of solution

for 1 gram we will take = 100 /37g of solution

for 0.146g we will take = 0.146 X 100 /37g= 0.395g of stock solution of 37%w/w HCl

The volume of this HCl = Mass / Density = 0.395 / 1.18 = 0.335 mL

total volume needed = 4 mL

so we will take 4-0.335 mL of D2O = 3.665 mL

Hence dissolve 0.395g of stock in 3.665 mL of D2O

2) Moles of KOH needed = Molarity X volume = 1 X 4 / 1000 = 0.004 moles

Mass of KOH needed = Moles X molar mass = 0.004 X 56.11 = 0.224 grams

So we will weight 0.224g of KOH pellets

Disslve this in 1mL of D2O first

Then make up the solution upto 4mL with D2O

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