The mass of 112 cm of `O_(2)` gas at STP is

Options

A. `0.16 g`
B. `0.8g`
C. `0.08g`
D. `1.6g`

Explanation

To find the mass of 112 cm³ of O₂ gas at STP, we can follow these steps:

### Step 1: Understand STP Conditions
STP stands for Standard Temperature and Pressure, which is defined as a temperature of 273 K (0°C) and a pressure of 1 atmosphere. Under these conditions, 1 mole of any ideal gas occupies a volume of 22.4 liters.

### Step 2: Convert Volume from cm³ to Liters
Since the volume given is in cm³, we need to convert it to liters. We know that:
1 cm³ = 1 mL
And,
1 L = 1000 mL

So, to convert 112 cm³ to liters:
\[ 112 \, \text{cm}^3 = 112 \, \text{mL} = \frac{112}{1000} \, \text{L} = 0.112 \, \text{L} \]

### Step 3: Calculate the Number of Moles of O₂
Using the molar volume of a gas at STP (22.4 L), we can find the number of moles of O₂ in 0.112 L:
\[ \text{Number of moles} = \frac{\text{Volume}}{\text{Molar Volume}} = \frac{0.112 \, \text{L}}{22.4 \, \text{L/mol}} \]
Calculating this gives:
\[ \text{Number of moles} = \frac{0.112}{22.4} \approx 0.005 \, \text{moles} \]

### Step 4: Calculate the Mass of O₂
Next, we need to find the mass of the oxygen gas using the molar mass of O₂. The molar mass of O₂ (oxygen gas) is approximately 32 g/mol. Therefore, the mass can be calculated as:
\[ \text{Mass} = \text{Number of moles} \times \text{Molar mass} = 0.005 \, \text{moles} \times 32 \, \text{g/mol} \]
Calculating this gives:
\[ \text{Mass} = 0.16 \, \text{g} \]

### Final Answer
The mass of 112 cm³ of O₂ gas at STP is **0.16 grams**.

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