At STP, we have the following data:
[tex]pV=\text{nRT}\begin{cases}p(\text{pressure)}=1\text{ atm} \\ V(volume)=172mL=0.172L \\ T(temperature)=0C=273\text{ K} \\ R=0.082\frac{L\cdot atm}{mol\cdot K} \\ n=mol\end{cases}[/tex]To find the mass, we need to find the mol. Based in the formula, we clear the n (mol) and replace the STP values there:
[tex]n=\frac{pV}{RT}=\frac{1atm\cdot0.172L}{0.082\frac{L\cdot atm}{mol\cdot K}\cdot273K}=0.00768molCO_2\text{.}[/tex]Finally, to find the mass, we use the molar mass where you can find it in the periodic table (C = 12 g/mol and O = 16 g/mol)
For CO2, we do the following calculation :
[tex]CO_2=1\cdot12\text{ g/mol }+2\cdot16\text{ g/mol=44 g/mol.}[/tex]Doing the conversion from mol to mass (grams):
[tex]0.00768molCO_2\cdot\frac{44gCO_2}{1molCO_2}\approx0.33792gCO_2.[/tex]The mass of CO2 in this sample is 0.34 g.
