Outline the procedure you would use to prepare a standard solution of sodium hydrogen carbonate from solid sodium hydrogen carbonate - HSC - SSCE Chemistry - Question 16 - 2004 - Paper 1
Question 16
Outline the procedure you would use to prepare a standard solution of sodium hydrogen carbonate from solid sodium hydrogen carbonate.
Calculate the mass of solid so... show full transcript
Worked Solution & Example Answer:Outline the procedure you would use to prepare a standard solution of sodium hydrogen carbonate from solid sodium hydrogen carbonate - HSC - SSCE Chemistry - Question 16 - 2004 - Paper 1
Step 1
Outline the procedure you would use to prepare a standard solution of sodium hydrogen carbonate from solid sodium hydrogen carbonate.
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Answer
Calculate the required amount of solid sodium hydrogen carbonate (NaHCO₃):
Determine the molar mass of sodium hydrogen carbonate, which is approximately 84.01 g/mol.
If you're preparing a solution of known molarity and volume, use the formula:
n=CimesV
where n is the number of moles, C is the concentration in mol/L, and V is the volume in liters.
For example, for a 0.1 mol/L solution in 1 L, n=0.1imes1=0.1 moles.
Calculate the mass:
extmass=nimesextmolarmass
Thus, the mass would be 0.1imes84.01extg=8.401extg.
Weigh the solid sodium hydrogen carbonate:
Use an electronic balance to accurately weigh out the calculated amount of sodium hydrogen carbonate.
Dissolve the solid in distilled water:
Add the solid to a clean beaker containing distilled water. Stir with a glass rod until completely dissolved.
Transfer to a volumetric flask:
Pour the solution into a 250 mL volumetric flask, rinsing the beaker with distilled water to ensure all solute transfers into the flask.
Make up to the mark:
Add distilled water to the volumetric flask until the bottom of the meniscus reaches the 250 mL mark. Stopper the flask and invert it several times to mix thoroughly.
Step 2
Calculate the mass of solid sodium hydrogen carbonate required to make 250 mL of 0.12 mol L⁻¹ solution.
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Answer
Calculate moles of NaHCO₃:
Use the formula:
n=CimesV
where C=0.12 mol/L and V=0.250 L, gives:
n=0.12imes0.250=0.03extmoles
Calculate the mass using molar mass:
Using the molar mass of sodium hydrogen carbonate (84.01 g/mol):