PART IV. DETERMINATION OF % PURITY of UNKNOWN should is Au this po Unknowm numbe

Question

PART IV. DETERMINATION OF % PURITY of UNKNOWN should is Au this po Unknowm number io 9.103 -b.esiB 2) Mass of vial+ sample pink colo 3) Finally, v pink cole Mass of vial after transfer Record the Mass ofunknown sample (impure KHP) this process starting eac Aliquot number Volume of impure KHP solution To det 20.00 mL. 20.00 mL 20.00 ml - Use t .Refc Cal final t you n the t stoie Volume of NaOH used Average Concentration of NaOH (from, Part III) Moles of NaOH used Moles of KHP in aliquot Moles of KHP per mL enem w PART Average moles of KHP per ml. Total moles of KHP (in volumetric flask) Mass of pure KHP Each imp repe lab the % purity dei Tr ne Actual % purity (filled in by instructor)

Explanation / Answer

Here the number of moles of KHP in 20 mL is 2.09*10^-3

Molarity = moles / volume in L

Molarity = 2.09*10^-3 moles / 0.020 L

= 0.1045 Moles per L

Now calculate the number of moles of KHP in 100 mL as follows:

Molarity * volume in L

= 0.1045 Moles per L *0.100 L

=0.01045 Moles

Molar mass of KHP = 204.22 g/mol

Mass of 0.01045 Moles = 0.01045 Moles *204.22 g/mol

=2.13 g

% purity = mass obtained / samples mass*100

= 2.13 g/3.0513 g*100

=69.94 %

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