Multiple Choice
Which of the following best illustrates the use of gas stoichiometry in a real-world application?
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7. Gases
Gas Stoichiometry
Multiple Choice
The oxidation of phosphorus can be represented by the following equation:
P4 (s) + 5 O2 (g) → 2 P2O5 (g)
If 1.85 L of diphosphorus pentoxide form at a temperature of 50.0 ºC and 1.12 atm, what is the mass (in g) of phosphorus that reacted?
A
4.84 g
B
7.02 g
C
10.9 g
D
12.4 g
E
17.7 g
Verified step by step guidance1
First, use the ideal gas law to find the number of moles of P2O5 formed. The ideal gas law is given by the equation: , where P is the pressure, V is the volume, n is the number of moles, R is the ideal gas constant, and T is the temperature in Kelvin.
Convert the temperature from Celsius to Kelvin by adding 273.15 to the Celsius temperature: .
Rearrange the ideal gas law to solve for n (moles of P2O5): . Use the given values: P = 1.12 atm, V = 1.85 L, R = 0.0821 L·atm/mol·K, and T in Kelvin.
Use the stoichiometry of the balanced chemical equation to find the moles of P4 that reacted. According to the equation, 2 moles of P2O5 are produced from 1 mole of P4. Therefore, the moles of P4 is half the moles of P2O5.
Finally, calculate the mass of phosphorus (P4) that reacted using its molar mass. The molar mass of P4 is approximately 123.88 g/mol. Multiply the moles of P4 by its molar mass to find the mass in grams.
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