Question

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

Answer 1

Answer:

• 0.150 grams

Explanation:

The balanced chemical reaction to obtain water from SnO₂ is:

• SnO₂ + 2H₂ → Sn + 2H₂O

The mole ratio is:

          $\dfrac{1molSnO_2}{2molH_2O}$

Find the number of moles equivalent to  1.20× 10²¹ molecules of water, using Avogadro's number:

         $1.20\times 10^{21}molecules\times \dfrac{1mol}{6.022\times 10^{23}molecules}=1.9927\times 10^{-3}moles$

From the mole ratio, the number of moles of SnO₂ are half the number of moles of water. That is:

• 0.0019927 moles / 2 = 0.00099635 moles of SnO₂

Use the molar mass of SnO₂ to convert the number of moles to grams:

• molar mass of SnO₂ = 150.71g/mol

• mass of SnO₂ = 0.00099635mol × 150.71 g/mol = 0.150 grams.

The answer must be reported with 3 significant figures.