Calculate the amount of (mol) of Rh in 1.69g of Rh. If the molar mass is 102.90?

1 Answer
Stefan V.
Feb 27, 2015

You have 0.01642 moles of rhodium, #"Rh"#, in #"1.69 g"# of #"Rh"#.

You know that #"Rh"#'s molar mass is #"102.90 g/mol"#. What that means is that 1 mole of rhodium weighs #"102. 9 g"#. If you compare that to 1.69 g, the mass given to you, it'll be obvious that you have less than 1 mole.

The exact number of moles of rhodium you have is

#"1.69 g Rh" * "1 mole"/"102.9 g" = "0.01642 moles Rh"#

Remember, molar mass expresses the weight of 1 mole of an element or substance; in this case, less than 102.9 g of rhodium will mean less than 1 mole, and more than 102.9 g will mean more than 1 mole.

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