We can measure the concentration of NaOH solution by reaction with KHP We can me
ID: 552324 • Letter: W
Question
We can measure the concentration of NaOH solution by reaction with KHP We can measure the concentration of NaOH solution by reaction with KHPComplete reaction with 0.9674 ± 0.0009 g of KHP (molecular weight: 204.2210 ± 0.0007 g/mol) required 27.35 ± 0.04 mL of NaOH. Find the molarity of the NaOH and its absolute uncertainty. o rNIP Ho (NaOH) (KHP) (NaKP) Complete reaction with 0.9674 ± 0.0009 g of KHP (molecular weight: 204.2210 ± 0.0007 g/mol) required 27.35 ± 0.04 mL of NaOH. Find the molarity of the NaOH and its absolute uncertainty.
Explanation / Answer
Given, mass of KHP = 0.9674 ± 0.0009 g, molar mass of KHP = 204.2210 ± 0.0007 g/mol
so, number of moles of KHP (nKHP) = Mass of KHP/ Molar mass of KHP
= (0.9674 ± 0.0009) / (204.2210 ± 0.0007)
= (0.9674 ± 0.093%) / (204.2210 ± 0.000343%)
[since, (0.0009 / 0.9674) *100 = 0.093%]
= (0.9674 / 202.2210) ± (0.093% + 0.000343 %)
= 0.00474 ± 0.093343%
= 0.00474 ± 0.0000044 moles
From the equation, it is apparent that, KHP and NaOH combine in 1:1 molar ratio,
so, nKHP = nNaOH = 0.00474 ± 0.0000044 moles
Molarity of NaOH = nNaOH/ Volume of NaOH (mL)
= (0.00474 ± 0.0000044) moles / 27.35 ± 0.04 mL
= 1000 * (0.00474 ± 0.0000044) / 27.35 ± 0.04 mol L -1
= (4.74 ± 0.0044) / (27.35 ± 0.04) mol L -1
= (4.74 ± 0.0928%) / (27.35 ± 0.146%) mol L -1
= (4.74 / 27.35) ± (0.0928% + 0.146%) mol L -1
= 0.1733 ± 0.2388 % mol L -1
= 0.1733 ± 0.0004138 mol L -1
so, molarity of NaOH is 0.1733 mol L -1 and its absolute uncertainty is 0.0004138
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