Mass to Mass Problems

Mass to mass problems involve one additional conversion to what was done earlier. Because there is no direct link between the mass of one substance to the mass of another, as illustrated below, we must go through the moles and ratio to achieve an answer. 

 

The guide above would require us to do our equations as seen in the examples below. 

Example One:

Aluminum is produced by the decomposition of Bauxite. What mass of aluminum can be produced from 2.04 kg of Aluminum oxide?  

• 2Al2O3 ----> 4Al + 3O2 
• 2.04 Kg = 2040 g  

• 2040g x (1 mol/102g) x (4/2) x (27.0g/1mol) = 1080g ---> 1.08 x 10^3 g of Aluminum

Example Two:

Sulphuric Acid reacts with Potassium hydroxide to produce Potassium sulphate and water. What mass of Potassium sulphate can be produced from 294.6g of Potassium Hydroxide?  

• 2NaI + 1Pb(NO3)2----> 2NaNO3 + 1PbI2 

• 150g x (1 mol/85.0g) x (1/2) x (331.2g/1mol) = 292 g of Potassium Sulphate 

Here is a supplementary video: 

 

- Simon Sierra