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

Răspuns :

[tex]m_s=500g[/tex]

[tex]c_1=5\%[/tex]

[tex]c_2=2\%[/tex]

[tex]m_{ad}=?[/tex]

[tex]c_1=\frac{m_d*100}{m_s}=\textgreater m_d=\frac{c_1m_s}{100}=25g[/tex]

[tex]c_2=\frac{m_d*100}{m_s+m_{ad}}[/tex]

[tex]c_2m_s+c_2m_{ad}=m_d*100[/tex]

[tex]c_2m_{ad}=m_d*100-c_2m_s[/tex]

[tex]m_{ad}=\frac{m_d*100-c_2m_s}{c_2}=750g[/tex]

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