[tex]m_{CO_2}=1 \ kg=1 \ 000 \ g \\ M_{CO_2}=12+16\cdot 2=12+32=44 \ g/mol \\ \nu=\frac{m}{M} \Rightarrow \nu_{CO_2}=\frac{1 \ 000 \ g}{44 \ g/mol}=22,73 \ moli; \\ a=\frac{n}{\nu} =6,023 \cdot 10^{23} \ molecule/mol; \\ \Rightarrow n_{CO_2}=a \cdot \nu_{CO_2}=6,023 \cdot 10^{23} \ molecule/mol \cdot 22,73 \ moli \\ \Rightarrow \boxed{n_{CO_2}=1,37 \cdot 10^{25} \ molecule}[/tex]
