What is the change in entropy when 0.290 g of silicon is burned in excess oxygen to yield silicon dioxide at 298 K?
Si(s) + O2(g) -> SiO2(s); ÄS° = –182.4 J/K at 298 K
delta S = -182.4 J for 28.08 g Si. What will it be for 0.290 g?
To calculate the change in entropy (ΔS) when silicon is burned to yield silicon dioxide, you can use the equation:
ΔS = n × ΔS°
Where:
- ΔS is the change in entropy
- n is the number of moles
- ΔS° is the standard entropy change
First, you need to determine the number of moles (n) of silicon (Si). To do this, you can use the molar mass of silicon (28.09 g/mol) and the given mass of silicon (0.290 g):
n = mass / molar mass
n = 0.290 g / 28.09 g/mol
Next, you substitute the value of n into the equation to calculate the change in entropy:
ΔS = n × ΔS°
The given value for the standard entropy change (ΔS°) is -182.4 J/K. However, you need to convert this value from joules per kelvin to joules per mole-kelvin by dividing by the molar mass:
ΔS = n × ΔS° / molar mass
Substituting the values:
ΔS = (0.290 g / 28.09 g/mol) × (-182.4 J/K) / (28.09 g/mol)
By calculating this expression, you can determine the change in entropy when 0.290 g of silicon is burned in excess oxygen to yield silicon dioxide at 298 K.