Question

AM NEVOIE URGENT!!!!

1cata sare s a dizolvat in 300g solutie, daca aceasta are concentratia de 40%?
2ce concentratie are solutia obtinuta prin dizolvarea a 200g zahar in 400g apa?
3ce concentratie are solutia prin amestecarea a 200g solutie 30% cu 300g solutie 10%?
4cata solutie de concentratie 30% se obtine prin dizolvarea a 100g zahar in apa?

Answer 1

1.

ms= 300g, c%= 40%

c% = mdx100/ms

=> md = msxc%/100 = 300x40/100 = 120g sare

2.

md= 200g, m.apa= 400g

ms = md+m.apa= 200+400 = 600g sol.

c%= mdx100/ms = 200x100/600 =  33,33%

3.

ms1= 200g, c1%= 30%

ms2= 300g, c2%= 10%

din c%

=> md1 = ms1xc1/100 = 200x30/100 = 60g

=> md2 = ms2xc2/100 = 300x10/100 = 30g

=> md.tot= md1+md2 = 60+30= 90 g

ms.tot= ms1+ms2 = 200+300 = 500 g

=> c%.final = md.totx100/ms.tot

= 90x100/500 = 18%

4.

md= 100g, c%= 30%

din c% => ms = mdx100/c%

= 100x100/30 = 333,33 g