What mass of CoS is produced from 4.84 g Co(NO3)2 and 115 mL of 0.225 M K2S solution? _____ g (Give answer to correct sig figs in units of g)

On Easter Sunday, April 3, 1983, nitric acid spilled from a tank car near downtown Denver, Colorado. The spill was neutralized with sodium carbonate: 2HNO3(aq)+Na2CO3(aq)2NaNO3(aq)+H2O(l)+CO2(g) a. Calculate H for this reaction. Approximately 2.0 104 gal nitric acid was spilled. Assume that the acid was an aqueous solution containing 70.0% HNO3 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? (Hf for NaNO3(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?

39. Standard solutions of calcium ion used to test for water hardness are prepared by dissolving pure calcium carbonate. CaCO3, in dilute hydrochloric acid. A 1.745-g sample of CaCO3 is placed in a 250.O-mL volumetric flask and dissolved in HCI. Then the solution is diluted to the calibration mark of the volumetric flask. Calculate the resulting molarity of calcium ion.

What is the final concentration of the solution produced when 225.5 mL of a 0.09988-M solution of Na2CO3 is allowed to evaporate until the solution volume is reduced to 45.00 mL?