We can measure the concentration of HCl solution by reaction with pure sodium carbonate: 2H+ + Na2CO3 --> 2Na+ + H2O + CO2. Complete reaction with 0.967 4 (+/- 0.000 9) g of Na2CO3 (FM 105.988 4 (+/- 0.000 7)) required 27.35 (+/- 0.04) mL of HCl. Find the molarity of the HCl and its absolute uncertainty.