Dau 100 puncte pe cel puțin 5 din ele....+coroniță.
Răspunsuri la întrebare
ti-am rezolvat 5 cele mai dificile din set.
7.
ms1= 800g, c1% = 10%
ms2= 500g, c2% = 5%
m.apa = 100g, m.sare= 50g
c%finala = md.finalx100/ms.finala
md1 = ms1xc1/100 = 800x10/100 = 80g
md2 = ms2xc2/100 = 500x5/100 = 25g
md.final = md1+md2+m.sare = 80+25+50 = 155g
ms.final = ms1+ms2+m.apa =800+500+100 = 1400g
=> c%final = 155x100/1400 = 11,1%
8.
Vs= 600 mL, ro=p= 1,2g/mL, c% = 25%
m.apa = 300g,
a)
stim ca p = ms/Vs => ms = pxVs = 600x1,2 = 720g sol
c% = mdx100/ms
=> md = msxc%/100 = 720x25/100 = 180g
=ms.final = ms+m.apa = 720+300 = 1020g
=> c%final = mdx100/ms.final
= 180x100/1020 = 17,65%
b)
Vs.final = ms.final/p = 720/1,05 = 685,7 mL sol
9.
Vs = 300 mL, p = 1,1 g/mL, c% = 10%
m.soda = 30g
a)
ms = pxVs = 300x1,1 = 330g sol.
md = msxc%/100 = 330x10/100 = 33g
md.final = md+m.soda = 33+30 = 63g
ms.final = ms+m.soda = 330+30 = 360g
=> c%final = md.finalx100/ms.final = 63x100/360 = 17,5%
b)
Vs.final = ms.final/p = 360/1,3 = 277 mL sol (rotunjit)
10.
Vs = 800 mL, p = 1,1 g/mL, c% = 15%
c%.final = 25%, p.final = 1,2 g/mL
ms = pxVs = 800x1,1 = 880 g sol
md = msxc%/100 = 880x15/100 = 132g
md.final = md+m.soda.adaugata = md+a = 132+a
ms.final = ms + a = 880+a
c%.final = md.finalx100/ms.final
=> 25 = (132+a)100/(880+a)
=> a = 352/3 = 117,3 g soda adugata
facem proba:
md.final = 132+117,3 = 249,3 g
ms.final = 880+117,3 = 997,3g
=> c%.final = 249,3x100/997,3 = 25% deci verifica calculele
=> Vs.final = ms.final/p.final = 997,3/1,2 = 831,1 mL sol.
11.
Vs = 900 mL, c% = 5%, p = 1,1 g/mL
c%.final = 25%, p.final = 1,15 g/mL
ms = pxVs = 900x1,1 = 990 g
md = msxc%/100 = 990x5/100 = 49,5 g
ms.final = ms-m.apa.evap. = ms-a = 990-a
c%final= mdx100/ms.final
25 = 49,5x100/(990-a)
=> a = 792 g apa evaporata
=> ms.final = 990-792 = 198g
facem preba:
md = 49,5g, ms.final = 198g
=> c%.final = 49,5x100/198 = 25% deci verifica calculele
=> Vs.final = ms.final/p.final = 198/1,15 = 172,2 mL sol.