Question

Question #8c9fd

Answer 1

It could be `"O"_2`

Explanation:

We're asked to identify the gas based on some gas measurements and it's mass.

What we can do is find the molar mass `M` of the gas, using the equation

`M = (dRT)/P`

where

• `d` is the density of the gas, in `"g/L"`. We're given that `4` `"g"` occupies `2.8` `"L"`, so the density is

`(4color(white)(l)"g")/(2.8color(white)(l)"L") = 1.43` `"g/L"`

• `R` is the universal gas constant, equal to `0.082057("L"•"atm")/("mol"•"K")`

• `T` is the absolute temperature of the gas, in `"K"`. Standard temperature is defined as `273.15` `"K"`

• `P` is the pressure of the gas, in `"atm"`. Standard pressure is usually for these types of problems defined as `1` `"atm"`

Plugging in known values, we have

`M = ((1.43"g"/(cancel("L")))(0.082057(cancel("L")•cancel("atm"))/("mol"•cancel("K")))(273.15cancel("K")))/(1cancel("atm"))`

`= color(red)(32.0` `color(red)("g/mol"`

To me, `sfcolor(red)("oxygen gas"` seems pretty close to this value, so it could be `"O"_2`.