\(\begin{array}{l}
2)\\
a)\\
Vr = \dfrac{{500 \times 30}}{{100}} = 150ml\\
b)\\
Vr = \dfrac{{400 \times 2,5}}{{100}} = 10ml\\
3)\\
a)\\
Vr = \dfrac{{200 \times 70}}{{100}} = 140ml\\
mr = 140 \times 0,8 = 112g\\
b)\\
Vr = \dfrac{{100 \times 28}}{{100}} = 28ml\\
mr = 28 \times 0,8 = 22,4g\\
4)\\
{C_2}{H_5}OH + {O_2} \to C{H_3}COOH + {H_2}O\\
Vr = \dfrac{{10000 \times 8}}{{100}} = 800ml\\
mr = 800 \times 0,8 = 640g\\
n{C_2}{H_5}OH = \dfrac{{640}}{{46}} = 13,913\,mol\\
mC{H_3}COOH = 13,913 \times 60 = 834,78g
\end{array}\)
