Trộn 60g dd NaOH 20% với 40g dd NaOH 30% ta thu được dd có nồng độ bao nhiêu%?

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Đáp án:

C%=24%

Giải thích các bước giải:

\(\begin{array}{l}
{m_{NaOH}}(20\% ) = \dfrac{{60 \times 20}}{{100}} = 12g\\
{m_{NaOH}}(30\% ) = \dfrac{{40 \times 30}}{{100}} = 12g\\
 \to C{\% _{NaOH}} = \dfrac{{12 + 12}}{{60 + 40}} \times 100\%  = 24\% 
\end{array}\)

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