A chemistry student weighs out 0.0792g of formic acid HCHO2 into a 250.mL volumetric flask and dilutes to the mark with distilled water. He plans to titrate the acid with 0.2000M NaOH solution.
Calculate the volume of NaOH solution the student will need to add to reach the equivalence point. Round your answer to 3 significant digits.
Chem question?
2017-10-31 1:16 pm
回答 (1)
2017-10-31 1:28 pm
Suppose that 25.0 mL of the HCHO₂ are pipetted for the titration.
Molar mass of HCHO₂ = (1.0×2 + 12.0 + 16.0×2) g/mol = 46.0 g/mol
No. of moles of HCHO₂ used in titration = [(0.0792 g) / (46.0 g/mol)] × (25.0/250) = 0.0001722 mol
HCHO₂ + NaOH → NaCHO₂ + H₂O
1 mole of HCHO₂ needs 1 mole of NaOH for complete neutralization.
No. of moles of NaOH solution needed = 0.0001722 mol
Volume of NaOH solution needed = (0.0001722 mol) / (0.2000 mol/L) = 0.00861 L = 8.61 mL
Molar mass of HCHO₂ = (1.0×2 + 12.0 + 16.0×2) g/mol = 46.0 g/mol
No. of moles of HCHO₂ used in titration = [(0.0792 g) / (46.0 g/mol)] × (25.0/250) = 0.0001722 mol
HCHO₂ + NaOH → NaCHO₂ + H₂O
1 mole of HCHO₂ needs 1 mole of NaOH for complete neutralization.
No. of moles of NaOH solution needed = 0.0001722 mol
Volume of NaOH solution needed = (0.0001722 mol) / (0.2000 mol/L) = 0.00861 L = 8.61 mL
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