At S.T.P., the density of nitrogen monoxide is

Options

A. `3.0 gL^(-1)`
B. `30gL^(-1)`
C. `1.3 gL^(-1)`
D. `2.68 gL^(-1)`

Answer

To find the density of nitrogen monoxide (NO) at standard temperature and pressure (STP), we can follow these steps:

### Step 1: Understand STP Conditions
STP stands for Standard Temperature and Pressure. The standard temperature is 273.15 K, and the standard pressure is 1 bar (approximately 0.987 atm).

### Step 2: Determine the Molar Mass of Nitrogen Monoxide
The molar mass of nitrogen monoxide (NO) can be calculated as follows:
- Molar mass of Nitrogen (N) = 14 g/mol
- Molar mass of Oxygen (O) = 16 g/mol
- Therefore, Molar mass of NO = 14 g/mol + 16 g/mol = 30 g/mol

### Step 3: Use the Ideal Gas Equation to Find Density
The ideal gas equation is given by:
\[ PV = nRT \]
Where:
- \( P \) = pressure
- \( V \) = volume
- \( n \) = number of moles
- \( R \) = ideal gas constant
- \( T \) = temperature

To find density (\( \rho \)), we can rearrange the equation:
\[ \rho = \frac{PM}{RT} \]
Where:
- \( \rho \) = density
- \( M \) = molar mass

### Step 4: Substitute Values into the Density Formula
Using the values:
- \( P = 0.987 \) atm (standard pressure)
- \( M = 30 \) g/mol (molar mass of NO)
- \( R = 0.0831 \) L·atm/(K·mol) (ideal gas constant)
- \( T = 273.15 \) K (standard temperature)

Substituting these values into the density formula:
\[ \rho = \frac{(0.987 \, \text{atm}) \times (30 \, \text{g/mol})}{(0.0831 \, \text{L·atm/(K·mol)}) \times (273.15 \, \text{K})} \]

### Step 5: Calculate the Density
Calculating the denominator:
\[ 0.0831 \times 273.15 \approx 22.414 \, \text{L·atm/mol} \]

Now substituting back into the density formula:
\[ \rho = \frac{(0.987 \times 30)}{22.414} \approx \frac{29.61}{22.414} \approx 1.32 \, \text{g/L} \]

### Final Answer
The density of nitrogen monoxide (NO) at STP is approximately **1.32 g/L**.

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