Question

chemistry 20
final exam 2025
name: ebteasam
gases

1. if 3.00 g of oxygen gas is held in a container at stp, then the volume of the

container must be
16.60 l
2.10 l
4.20 l
22.4 l

Explanation:

Step1: Calculate the number of moles of oxygen

The molar mass of \(O_2\) is \(M = 32\space g/mol\). The number of moles \(n=\frac{m}{M}\), where \(m = 3.00\space g\). So \(n=\frac{3.00\space g}{32\space g/mol}=\frac{3}{32}\space mol\)

Step2: Use the molar volume at STP

At STP (Standard Temperature and Pressure: \(T = 273\space K\), \(P= 1\space atm\)), the molar volume of an ideal gas \(V_m=22.4\space L/mol\). The volume of the gas \(V=n\times V_m\). Substitute \(n = \frac{3}{32}\space mol\) and \(V_m = 22.4\space L/mol\) into the formula: \(V=\frac{3}{32}\space mol\times22.4\space L/mol\)

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Answer:

2.10 L