Question

Se amesteca 2 solutii c1=10 la suta c2=20 la suta . In ce proportie trebuie amestecate pt a obtine a) c3=15 b)c3=12 la suta c) c3=18la suta

Answer 1

solutia 1 : ms1      c1 = 10%  md1 = 0,1ms1
solutia 2:  ms2      c2 = 20%  md2 = 0,2ms2
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ms final = ms1 + ms2      md = md1+md2     
 (c1ms1 + c2ms2)·100/(ms1+ms2) = c final
notam ms1/ms2 = r
(10r + 20)/(r+ 1) = c         10r + 20 = cr +c          r(c-10) = 20 - c    r = (20-c)/(c-10)
a) r = 5/5 = 1/1    ms1 = ms2
b) r = 8/2 = 4      ms1 = 4ms2
c) r = 2/8 = 1/4    ms2 = 4ms1