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

1 Answer
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"