Respuesta :
The balanced reaction to produce lithium oxide is:
[tex]4Li+O_2\rightarrow2Li_2O[/tex]To produce 2 moles of lithium oxide, 4 moles of lithium and 1 mole of oxygen are needed.
The first step to solve these questions is to convert the mass of lithium to moles using its molecular weight (MW=29.88g/mol):
[tex]500g\cdot\frac{molLi_2O}{29.88g}=16.73molLi_2O[/tex]a. Use the ratio of moles of lithium to moles of lithium oxide to find how many moles of lithium are needed to produce 16.73moles of lithium oxide:
[tex]16.73molLi_2O\cdot\frac{4molLi}{2molLi_2O}=33.46molLi[/tex]Convert this to mass using lithium molecular weight:
[tex]33.46molLi\cdot\frac{6.94g}{molLi}=232.21g[/tex]232.21 grams of Lithium are needed.
b. Follow the same procedure to find the moles of O2 needed:
[tex]16.73molLi_2O\cdot\frac{1molO_2}{2molLi_2O}=8.365molO_2[/tex]At this point we can use the ideal gas law to find the volume occupied by 8.365 moles of O2. Use STP (P=1atm, T=273.15K) and R as 0.082atmL/molK:
[tex]\begin{gathered} PV=nRT \\ V=\frac{nRT}{P} \\ V=\frac{8.365mol\cdot0.082atmL/molK\cdot273.15K}{1atm} \\ V=187.36 \end{gathered}[/tex]It means that 187.36L of O2 are needed.
