7. A water solution of sulfuric acid (H2SO4) has a density of 1.67 g/mL and is 7

Question

7. A water solution of sulfuric acid (H2SO4) has a density of 1.67 g/mL and is 75 percent H250, by mass. How many moles of H2SO, are contained in 500. mL of this solution? Cobalt chloride (CoCl2) exists as a hydrate (has non-covalently bound waters of hydration) with a molecular mass of 237.93. Prolonged heating can drive off the waters of hydration. A 54.8 g sample of the hydrate was heated for 15 minutes, cooled and reweighed. The residual mass was found to be 33.2 g Calculate the number of water molecules associated with each CoCh2 in the hydrate. 8.

Explanation / Answer

Ans 7

Density of H2SO4 = 1.67 g/mL x 1000mL/L = 1670 g/L

Mass of H2SO4 per L = 1670 x 0.75 = 1252.5 g/L

Moles of H2SO4 per L = 1252.5 g/L x 1mol/98g

= 12.78 mol/L

Moles of H2SO4 in 500 mL solution = molarity x volume

= 12.78 mol/L x 500 mL x 1L/1000 mL

= 6.39 mol

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