Question

When elemental silicon is reacted with aqueous sodium hydroxide and liquid water at high temperature, sodium silicate and hydrogen gas are formed.

a. How many mL of 6.00M sodium hydroxide is needed to react with 12.5 g of silicon?

b. How many mL of hydrogen gas will be produced if the density of hydrogen gas is 0.08988 g/L

Answer 1

a. No. of moles of silion that has to be reacted: (Atomic weight = 28)

Si(s) + 4NaOH(aq) → [SiO₄]^4-(aq) + 4Na⁺(aq) + 2H₂(g)

from this equation, we can see that one mole of silicon requires 4 moles on NaOH.

0.4464 moles requires: 0.4464 * 4 = 1.7856 moles NaOH

We are gives 6M solution. Volume of NaOH solution containing 1.7856M NaOH is:

  

0.2976 liters or 297.6 mL

b. One mole silicon reacts to give 2 moles hydrogen gas. So, 0.4464 moles gives 0.8928 moles of hydrogen.

weight of one mole of hydrogen (atomic mass = 1 g/mole)

weight of hydrogen will be =

Therefore the volume of hydroen produced will be=