Question

se amesteca 10g solutie de concentratie 2% cu 40g solutie de concentratie 10% si cu 30g apa. care este concentratia finala?

Answer 1

ms1= 10 g , c1= 2%

ms2= 40 g , c2= 10%

m.apa = 30 g

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c.final= ?%

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stim ca c% = mdx100/ms

=> md1= ms1xc1/100 = 10x2/100 = 0,2 g

=> md2= ms2xc2/100 = 40x10/100 = 4 g

=> md.final = md1+ md2 = 0,2+4 = 4,2 g

ms.final = ms1 + ms2 + m.apa = 10+40+30 = 80 g

=> c.final = md.finalx100/ms.final

= 4,2x100/80 = 5,25%