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A solution of HNO3 is standardized by reaction with pure sodium carbonate 2H++ Na2CO3 2Na++H2O + CO2 A volume of 28.46 ± 0.05 mL of HNO3 solution was required for complete reaction with 08769 ± 0 0007 g of Na2CO3, (FM 105.988 ± 0.001). Find the molarity of the HNOg and its absolute uncertainty. Na-cos. (FM 105 Note: Significant figures are graded for this problem. To avoid rounding errors, do not round your answers until the very end of your calculations. Number Number

Explanation / Answer

V = 28.46 +/- 0.05 mL

2 mol of HNO3 requires 1 mol of Na2CO3

2 * Molarity * Volume( in L) =   moles of Na2CO3 = mass of Na2CO3 / Molar mass of Na2CO3

First calculate original molarity

2 * M * 28.46 / 1000 = 0.8769 / 105.988

M = 0.8769 * 1000 / (28.46 * 105.988 * 2)

M = 0.1453 mol / L

Absolute Uncertainty = 0.0007 + 0.001 + 0.05 = 0.05170

Molarity = 0.1453 +/- 0.05170 mol/L

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