Question

Calculate the mass of 1 cm³ of oxygen kept at STP.

Answer 1

We know that 22.4 L of O₂ contains 1 mol O₂ at STP. Thus,

\[22.4 \times  {10}^3    {\text { cm }}^3   \text {of   O}_2  = 1  \text { mol   O}_2 \] 

\[1   {\text { cm }}^3 \text{  of   O}_2    =   \frac{1}{22.4 \times {10}^3} \text{ mol   O}_2 \] 

\[1  \text { mol  of   O}_2    =   32  \text { g }\] 

\[\frac{1}{22.4 \times {10}^3}\text { mol  of   O}_2     = \frac{32}{22.4 \times {10}^3} = 1 . 43 \times  {10}^{- 3}   g\] \[=   1 . 43 \text{ mg }\]