Pure sodium metal reacts violently with water according to the equation below Na + H2O - NaO + H2
17 mol
If 0.75 mol of Na is placed in 500 g of
H, O how many moles of hydrogen
gas will be produced?
0.75 mol
28 mol
1.5 mol

0.75 mol

Explanation:

Given data:

Number of moles of Na = 0.75 mol

Mass of water = 500 g

Moles of hydrogen gas produced = ?

Solution:

Chemical equation:

Na + H₂O   →      NaO + H₂

Number of moles of water:

Number of moles = mass/molar mass

Number of moles = 500 g/ 18 g/mol

Number of moles = 27.8 mol

now we will compare the moles of hydrogen gas with both reactant.

                   Na         :          H₂

                    1            :          1

                  0.75       :         0.75

                 H₂O        :          H₂

                   1            :           1

               27.8          :         27.8

sodium will act as limiting reactant it produced small number of moles of hydrogen gas as compared to water.

Thus, number of moles of hydrogen gas are 0.75 mol.

the formula mass of a molecule or a compound is the sum of the atomic weights of the atoms in its empirical formula

(that's what i know about formula mass)

c) should be the answer.