Question

Help! What did I do wrong??

Solid sodium reacts violently with water, producing heat, hydrogen gas, and sodium hydroxide. How many molecules of hydrogen gas are formed when 48.7 g of sodium are added to water? Show your work. (4 points)

2Na + 2H2O ---> 2NaOH + H2


2Na + 2H2O ---> 2NaOH + H2

48.7 g ? molecules


2 mol Na= 1 mol H2

1 mol Na= 23g Na

1 mol H2= 6.02x1023 molecules


(48.7g Na/1)x(1 mol Na/23g Na)x(1 mol H2/2mol Na)x(6.02x1023/1 mol H2)


(48.7)(6.02x1023)/(23)(2)= 293.174x1023 molecules



Can someone please tell me what I did 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