Question

Help! What did I do wrong??

Answer 1

The molecules  of hydrogen gas that are  formed is  when 48.7 g  of sodium are added to water  is  6.375  x 10²³  molecules

  calculation

2 Na +2H₂O →  2 NaOH  +H₂

Step 1: find the moles  of sodium (Na)

moles =mass÷   molar mass

from periodic table the molar mass of Na = 23 g/mol

moles= 48.7 g÷ 23 g/mol =2.117 moles

Step 2:use the mole ratio to determine  the  moles of H₂

  from  given equation  Na:H₂ is 2:1

therefore the moles  of H₂ = 2.117 moles x 1/2=1.059 moles

Step 3: find the molecules of H₂ using the Avogadro's law

According  to  Avogadro's  law  1 mole = 6.02 x 10²³ molecules

                                                      1.059 moles = ?  molecules

by cross multiplication

= [(1.059 moles x 6.02 x10²³  molecules) /  1 mole] =6.375  x 10²³  molecules