On Easter Sunday, April 3, 1983, nitric acid spilled from a tank car near downtown Denver, Colorado. The spill was neutralized with sodium carbonate: 2 HNO 3 ( a q ) + Na 2 CO 3 ( a q ) → 2 NaNO 3 ( a q ) + H 2 O ( l ) + CO 2 ( g ) a. Calculate ∆ H° for this reaction. Approximately 2.0 ×10 4 gal nitric acid was spilled. Assume that the acid was an aqueous solution containing 70.0% HNO 3 by mass with a density of 1.42 glcm3. What mass of sodium carbonate was required for complete neutralization of the spill, and what quantity of heat was evolved? ( Δ H f ° for NaNO 3 (aq) = −467 kJ/mol) b. According to The Denver Post for April 4, 1983, authorities feared that dangerous air pollution might occur during the neutralization. Considering the magnitude of ∆ H°, what was their major concern?

Interpretation: The edge length of the cube of uranium should be determined.

Hess's Law:

Standard enthalpy of formation:

• The change in enthalpy that associate with the formation of one mole of a product from its pure elements, substances in which all its standard states is called as a standard enthalpy of formation.
• Formula:

               ΔHf = ∑npΔH°f(products)-∑nrΔH°f(reactants)......(1)

• Internal energy change of a reaction is given as,

To calculate the enthalpy change of the neutralization reaction

Given data:

                           Volume of Nitric acid is 2.0 ×104 gal

                            Nitric acid concentration is 7000

                            Nitric acid density is 1.42 gl cm3

                           Enthapy of formation of NaNO3(aq) is -467 kJ/mol

Neutralization reaction is,

                  2HNO3(aq)+NaCO3(s)→2NaNO3(aq)+H2O(l)+CO2(g)

                      ΔΗ°= [2(-467 kJ)+(-286 kJ)+(-393.5 kJ)]-[2(-207kJ)+(-1131 kJ)]           = -69 kJ

• The standard enthalpy of formation values are taking in to standard data and these are plugging in to equation (1) to give enthalpy change of the neutralization reaction.
• The enthalpy change of the neutralization reaction is -69 kJ.

To calculate the mass of Nitric acid.

                      MassNHO3= 2.0×104gallons×4 qtgal×946 mLqt×1.42 gmL                    = 1.1×108g

• The volume of the Nitric acid is converted by mass by converting unites for g/mL.
• The mass of Nitric acid is 1.1×108g.

To calculate the mass of 70% Nitric acid.

                    =MassHNO3 (g)70.0 g HNO3100.0 g solution= 1.1×108g×70.0g100.0 g= 7.7×107g

• The calculated mass of Nitric acid is plugging in above equation to give mass of 70% Nitric acid solution

Interpretation: The edge length of the cube of uranium should be determined.

Hess's Law:

Standard enthalpy of formation:

• The change in enthalpy that associate with the formation of one mole of a product from its pure elements, substances in which all its standard states is called as a standard enthalpy of formation.
• Formula:

               ΔHf = ∑npΔH°f(products)-∑nrΔH°f(reactants)......(1)

• Internal energy change of a reaction is given as,