How many moles are there in #"5.3 g"# of #"KNO"_3# ?

1 Answer
Sabrina S. · Stefan V.
Feb 20, 2018

It is #0.052# moles. You need to use the molar masses to convert from grams to moles.

Explanation:

You need to first find the molar mass of #"KNO"_3#. You do this by adding the individual molar mass of each element, these can be found on a periodic table or online.

#M_K = "39.0983 g/mol"#
#M_N= "14.0067 g/mol"#
#M_O = "15.999 g/mol"#

The molar mass is the sum of all of the elements times the number of moles of each element.

#M_ ("KNO"_3)= M_K + M_N + 3M_O#

#M_ ("KNO"_3)= ("39.0983 g/mol") + ("14.0067 g/mol") + 3("15.999 g/mol")#

#M_ ("KNO"_3) = "101.102 g/mol"#

Use

#n=m/M#

where:

  • #n=#number of moles
  • #m=#mass
  • #M=#molar mass

So

#n="5.3g"/"101.102 g/mol"#

# n = "0.052 moles"#

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