SnO2 + 2 H2 ——> Sn + 2 H2O

How many grams of SnO2 are required to produce 1.20x10^21 molecules of water?

0.15g

Explanation:

Given parameters:

Number of molecules of water = 1.2 x 10²¹ molecules

Unknown:

Mass of SnO₂  = ?

Solution:

To solve this problem, we have to work from the known to the unknown specie;

             SnO₂   +    2H₂    →   Sn  +   2H₂O

Ensure that the equation given is balanced;

Now,

          the known species is water;

                  6.02 x 10²³ molecules of water  = 1 mole

                   1.2 x 10²¹ molecules of water  =    = 0.2 x 10⁻²moles

Number of moles of water  = 0.002moles

           From the balanced chemical equation:

             2 mole of water is produced from 1 mole of    SnO₂  

           0.002 moles of water will be produced from  = 0.001moles

To find the mass;

           Mass  = number of moles x molar mass

Molar mass of  SnO₂ = 118.7 + 2(16) = 150.7g/mol

        Mass  =  0.001 x 150.7 = 0.15g