What is the molecular weight of #H_3PO_4#?

1 Answer
Nov 29, 2015

If you take a look at a periodic table, let #Z# be the atomic number and #MM# be the molar mass of atom #X#:

#Z_"H" = 1#
#MM_"H" = 1.0079#

#Z_"P" = 15#
#MM_"P" = 30.974#

#Z_"O" = 8#
#MM_"O" = 15.999#

Just note how many of each atom is in the compound, and add accordingly. For instance, there are four oxygen atoms.

http://www.ptable.com/

If you want to check your answer, just google the compound.