Caroline knows the amount of a compound in moles. to find the number of molecules in the given sample of her compound, which of which of the following must also be used in her calculation? atomic mass of each element in the compound mass of the sample in grams

Avogadro's number is used.

Explanation:

To know the number of molecules of any compound and the number of moles is known, the most ideal is to use the Avogadro number, which is defined as 6.022x10^23 molecules on one mole of any compound. If we do the conversion with the number of moles, we will obtain the number of molecules of the compound that we want.

1. for the first question, we must find the mass of the anhydrous salt, mgso₄. the molar mass for mgso₄·7h₂o is 246.47 g/mol, while that of mgso₄ is 120.37 g/mol.7.834 g mgso₄·7h₂o * 1 mol mgso₄·7h₂o/246.47 g * 1 mol mgso₄/1 mol mgso₄·7h₂o * 20.37 g mgso₄/mol = 0.647 g mgso₄

2. mass of water = mass of sample - mass of anhydrous salemass of water = 7.834 - 0.647 = 7.19 gpercent water in hydrate = 7.19/7.834 * 100 = 91.74%

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