Question

1. Cat clor contine 580g de solutie de acid clorhidric de concentratia 36,5%?
2. Cate grame de potasiu se gasesc in 405g de clorat de potasiu?
3. Se dau 10g de neon.Aflati numarul de moli.

Answer 1

1.

Concentrația procentuală a unei soluții: C/100 = md/ms , unde:

md - masa subst. dizolvate ; ms - masa soluției

$m_s_{HCl}=580g\\C=36.5\%\\M_{HCl}=A_{H}+A_{Cl}=1+35.5=36.5g/mol\\\\\frac{C}{100}=\frac{m_d}{m_s}\implies\ m_d=\frac{m_s*C}{100}=\frac{580*36.5}{100}=\frac{21170}{100}=211.7g\ HCl\\\\36.5g\ HCl\ contin\  35.5g\ Cl\\\\211,7g\ HCl\ vor\ contine\ x\ g\   Cl \\ \\ x=\frac{35.5*211.7}{36.5}=205.9g\ Cl$

2.

Cloratul de potasiu: KClO₃

$m_{KClO_3}=405g\\M_{KClO_3}=A_K+A_{Cl}+3*A_O==39+35.5+(3*16)=74.5+48=122.5g/mol\\\\122.5g\ KClO_3\ contin\ 39g\ K\\\\405g\ KClO_3\ vor\ contine\ x\ g\ K\\\\x=\frac{39*405}{122.5}=128.93g\ K$

3.

$m_{Ne}=10g\\M_{Ne}=20g/mol\\\\1\ mol\ Ne\ contine 20g\\\\x\ moli\ Ne\ vor\ contine\ 10g\\\\x=\frac{1*10}{20}=0.5\ moli\ Ne$