Respuesta :
Answer : The molecular weight of a gas is, 128.9 g/mole
Explanation : Given,
Density of a gas = 5.75 g/L
First we have to calculate the moles of gas.
At STP,
As, 22.4 liter volume of gas present in 1 mole of gas
So, 1 liter volume of gas present in [tex]\frac{1}{22.4}=0.0446[/tex] mole of gas
Now we have to calculate the molecular weight of a gas.
Formula used :
[tex]\text{Moles of gas}=\frac{\text{Mass of a gas}}{\text{Molecular weight of a gas}}[/tex]
Now put all the given values in this formula, we get the molecular weight of a gas.
[tex]0.0446mole=\frac{5.75g}{\text{Molecular weight of a gas}}[/tex]
[tex]\text{Molecular weight of a gas}=128.9g/mole[/tex]
Therefore, the molecular weight of a gas is, 128.9 g/mole
128.8 g/mole.
Further explanation
Given:
Density of a gas = 5.75 g/l at STP
Question:
The molecular weight of this gas (in g/mol)
The Process:
This is a stoichiometric calculation.We will find out the molecular weight (or molar mass) of the gas measured at STP with known density.
Remember at STP 1 mole of gas = 22.4 L or referred to as a molar volume.
From the value of the gas density, we know that 1 L of gas has a mass of 5.75 g.
- Volume of gas = 1 L
- Mass of gas = 5.75 g
- Molar volume = 22.4 L/mole
The relationship between the mole (n), mass (m), molecular weight (M), volume (V), and molar volume (Vm) is as follows:
[tex]\boxed{ \ n = \frac{V}{V_m} \ } \ and \ \boxed{ \ n = \frac{mass}{molecular \ weight} \ } \rightarrow \boxed{\boxed{ \ \frac{mass}{molecular \ weight} = \frac{V}{V_m} \ }}[/tex]
Let us calculate the molecular weight.
[tex]\boxed{ \ \frac{m}{M} = \frac{V}{V_m} \ }[/tex]
[tex]\boxed{ \ M = \frac{m \times V_m}{V} \ }[/tex]
[tex]\boxed{ \ M = \frac{5.75 \times 22.4}{1} \ }[/tex]
[tex]\boxed{\boxed{ \ M = 128.8 \ }}[/tex]
Thus the molecular weight of a gas that has a density of 5.75 g/L at STP equal to 128.8 g/mole.
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Notes:
- STP (in chemistry) is the abbreviation for Standard Temperature and Pressure, i.e., 273 K (0° Celsius or 32° Fahrenheit) and 1 atm.
- Remember the mole number of a substance can be found via mass, volume, or number of particles.
Learn more
- At STP, what is the volume of nitrogen gas? https://brainly.com/question/4294791
- Conservation of mass https://brainly.com/question/9473007
- What is the formula for the hydrate? https://brainly.com/question/13012523
