Question

Determinati concentratia molara a solutiilor care contin: 
a)  2 moli H₂SO₄ in 250 cm³ solutie;
b)  400g NaOH in 5L solutie;
c)  196g H₂SO₄ in 200g solutie cu ρ[ro] =1,84 g/cm³
 
Va rog mult sa ma ajutati :(  Multumesc! :x

Answer 1

a)cM=nr moli/volum=2/0,25=>cM=8 moli/litru
b)cM=m NaOH/(masa molara NaOH * volum)=400/(40*5)=>cM=2 moli/litru
c)=(md/ms)*100=(196/200)*100=98%
cM=(c% * ro * 10)/ masa molara H2SO4=(98 * 1,84 * 10 )/98=>cM=18,4 moli/litru

Answer 2

a) Cm=nr moli/volum=2/0,25=8 M  250 cm cubi=? dm cubi= 250:1000=0,25
b) n=m/M=400/40=10 moli NaOH
Cm=n/V=10/5=2M ( 2 moli/L)
c) ro s=ms/vs=> vs=ms/ros= 2008/1,849= 108,6 cm cubi
Cm=nr moli/Vs=2/0,1=20 M
MH2SO4=2*1+1*32+4*16= 2+32+64=98g/mol