An aqueous solution of orthophosphoric acid, H3PO4, has a measured density of 1.2089 g mL-1 and is 5.257 molal. The solution is 34.0% phosphoric acid. How many moles of H3PO4 are there in one liter of this solution?

In one liter of solution, there are 4.194 moles of H₃PO₄

Explanation:

A molal solution contains 1 mole of solute in 1 Kg of solvent.

A  aqueous 5.257 molal solution of H₃PO₄ will contain 5.257 moles of  H₃PO₄ in 1 Kg or 1000 g of water .

Molar mass of H₃PO₄ = 98 g/mol

Therefore mass of H₃PO₄ = number of moles * molar mass

mass of H₃PO₄ = 5.257 mol * 98 g/mol = 515.2 g

mass of solution = mass of solute + mass of solvent

mass of solution = 515.2 + 1000 = 1515.2 g

Volume of solution = mass of solution / density of solution

Volume of solution = 1515.2 / 1.2089 = 1253.4 mL

Molarity of solution = number of moles / volume (L)

Molarity of solution = 5.257 / 1.2534 L = 4.194 mol/L

Therefore, in one liter of solution, there are 4.194 moles of H₃PO₄

personal, she chose to do it.

definition

                    entropy is a measure of the randomness or the extent of disorder of a chemical process.

                      enthalpy is a measure of the heat change of a reaction occurring at a constant pressure.

measurement units:

                        entropy is measured in joule per kelvin (jk⁻¹)   whereas enthalpy is measured in joule per mole (jmol⁻¹)

requirements:

                            entropy has no requirements or limits, and its change is measured by the division between the heat change of the chemical process and the temperature.

                              in contrast, enthalpy can only be related to the heat change of the reaction under standard conditions.