Calculate the percentage composition of Ca(MnO4)2.
Firstly, we see how many atoms are there for each element in the formula.
Ca= 1 atom
Mn= 2 atoms
O= 8 atoms
Next, we are going to consult our periodic table for the atomic mass of each element.
Ca= 40
Mn= 55
O= 16
Then, we have to find the molar mass for the compound..
Here is the formula for calculating molar mass of an element:
Molar Mass= ( no. of atoms of the element × atomic mass of the element)
Now, we have to calculate the atomic mass of the compound. So using the molar mass formula for an element, we calculate the molar mass for each element then we sum up their molar masses to get the compounds molar mass.
Molar mass (Ca)= 1× 40
(Ca)= 40
Molar mass (Mn)=2×55
(Mn)= 110
Molar mass (O)= 8×16
(O)= 128
Now: Molar mass( compound)= (Ca)+(Mn)+(O)
= 40+ 110 128
= 278
This is everything we need to calculate our percentage composition for each element..
* The example says to find the percentage composition for Ca. So we only find for Ca, Which is already done using the formula and the answer is 14.39%.
To prove that your answer is correct, find the percentage composition for Mn and O as well. Then you add up their percentage compositions.
If you do and you get 100 as your answer, then your percentage compositions are correct.
Why don't you try finding the percentage composition for Mn and O, then add up all the three percentage compositions. If you 100 as their sum, then your percentage composition for each of the elements are correct.
