Question

Cata apa trebuie adaugata,la 500g solutie de soda,de concentratie 5%, pentru a dilua la 2% ?

Answer 1

$m_s=500g$

$c_1=5\%$

$c_2=2\%$

$m_{ad}=?$

$c_1=\frac{m_d*100}{m_s}=\textgreater m_d=\frac{c_1m_s}{100}=25g$

$c_2=\frac{m_d*100}{m_s+m_{ad}}$

$c_2m_s+c_2m_{ad}=m_d*100$

$c_2m_{ad}=m_d*100-c_2m_s$

$m_{ad}=\frac{m_d*100-c_2m_s}{c_2}=750g$