Question

2. Very thin layers of silicon can be added to smooth solid surfaces by a process called chemical vapor deposition (CVD). In CVD a reaction occurs in the gas phase and a solid product is produced, which then deposits on a surface. If 1.00 L of silane gas (SiH4) are allowed to react in a container at a temperature of 600.°C and a pressure of 75 Pa, how many grams of solid silicon will be produced? Silane reacts according to the following equation. (15 points) SiH4(g)  Si(s) + 2 H2(g)

Answer 1

Answer: The reaction will produce 0.0003 g of solid silicone.

Step-by-step explanation: Use Ideal Gas Law to determine how many mols of SiH4 there are in the reaction. The formula for the Law is:

PV = nRT

where:

P is pressure in atm

V is volume in L

n is mols

R is gas constant, R = 0.082 L.atm.mol⁻¹.K⁻¹

T is temperature in K

First, transform the variables to units that equals the constant unit:

Pressure:

Pa in atm: P =
`(73)/(101325)` = 0.00074 atm

Temperature:

°C in K: T = 600 + 273.15 = 873.15 K

With those values, determine the mols (n):

PV = nRT

n =
`(PV)/(RT)`

n =
`(0.00074)/(0.082.873.15)`

n = 0.00000103 mols

From the balanced reactio equation, 1 mol of silane produces 1 mols of solid silicone, so, 0.00000103 mols of silane produces 0.00000103 mol of solid silicone.

To find the mass in grams:

Si has molar mass of 28.0855g/mol

1 mol = 28.0855 g

0.00000103 mols = m

m = 28.0855*0.00000103

m = 0.0003 grams

It will be produced 0.0003 grams of solid silicone