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Home Q & A Board Science-Related Homework Help Chemistry (Moderator: Laser_3)
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smmunday smmunday
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11 years ago
Mg3(PO4)2

Also, what is the scientific notation of 0.000786?
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wrote...
#1
11 years ago
Find the molar mass of Mg3(PO4)2, then multiply by Avogadro's number (6.022x10^23), the number of molecules/atoms in 1 mol of anything.

Sci Not 0.000786 = move decimal point right to the first non zero digit, count how many places you moved.  This # is your exponent.  Since you are moving to the right, the exponent will be negative.  Now you have 7.86 x 10^-4.
wrote...
#2
11 years ago
If you consider only one molecule of Mg3(PO4)2, there are a total of 13 atoms: 3 Mg, 2 P, 8 O.
You can use Avogadro's number to determine the total number of molecules in a compound for a given mass of that molecule.  Since the problem neither gives you a mass nor does it ask you how many number of molecules there would be in x number of moles, you do not need to worry about those calculations.
wrote...
#3
11 years ago
That's a bit tricky, since magnesium phosphate does not exist in discrete molecules, but in an extended network of magnesium atoms and phosphate radicals.

But if it did exist as a discrete molecule, there are three atoms of Mg and 2 atoms of P, and 8 atoms of O..  That would be a total of 13 atoms per "molecule".

Scientific notation:  7.86 x 10^-4
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