Question

65. Because carbon and silicon are both elements in group 14 on the periodic table, we expect them to react with other elements in similar ways. To some extent, then do, but in some cases, carbon and silicon compounds that seem to have analogous structures have very different chemical characteristics. For example, carbon tetrachloride, CCl₄ is very stable in the presence of water, but silicon tetrachloride, CCl₄, reacts quickly with water. The unbalanced equation for this reaction is

                SiCl₄ + H₂O à Si(OH)₄ + HCl

1. Balance this equation.
2. Write a conversion factor that could be used to convert between moles of SiCl₄ and moles of H₂O
3. How many moles of SiCl₄ react with 24 moles of water?
4. Write a conversion factor that could be used to convert between moles of Si(OH)₄ and moles of water.
5. How many moles of Si(OH)₄ form when 4.01 moles of H₂O react with an excess of SiCl₄?

Answer 1

Ans:

a. The correct balanced equation can be written as below:

2SiCl4 + 8H2O --- > 2Si(OH)4 + 8HCl

b. Write a conversion factor that could be used to convert between moles of SiCl4 and moles of H2O

From (a) it is clear that two moles of SiCl4 reacts with eight moles of water. Equating it to 1, then the conversion factor will be

= 2/8 = 0.25

c. How many moles of SiCl4 react with 24 moles of water?

Applying the conversion factor, we can calculate as follows:

Number of moles of SiCl4 that will reacts with 24 moles of water

= 24 * 0.25 = 6 moles

d. Write a conversion factor that could be used to convert between moles of Si(OH)4 and moles of water.

As done above, we know that 2 moles of Si(OH)4 are produced from 8 mole of water.

Hence the conversion factor would be = 2/8 = 0.25.

Means, 0.25 moles of Si(OH)4 will be produced from one mole of water or vice versa.

e. How many moles of Si(OH)4 form when 4.01 moles of H2O react with an excess of SiCl4?

Applying the conversion factor, we can calculate as follows (water is a limiting factor for conversion):

Number of moles of Si(OH)4 that will form with 4.01 moles of water reacting with the excess of SiCl4

(applying the conversuion factor)

= 4.01 * 0.25 = 1.0025 moles of Si(OH)4