Question

Citește formulele:a) 4HCl; b)CO2; c)6H2O; d)2P2O5 e)3NaOH; f)5H2SO4.
Calculează:1) numărul de atomi ai fiecărui element; 2) masa moleculară relativă a fiecărei substanțe...)

Answer 1

I.
a) HCl - acid clorhidric

b) CO2 - dioxid de carbon

c) H2O - apa

d) pentaoxidul de fosfor

e) hidroxid de sodiu (soda caustica)

f) H2SO4 - acid sulfuric (vitriol)

1. 4HCl - 4 atomi de H si 4 atomi Cl

1mol H......................6,022*10^23 atomi
4mol........................x=Calculeaza si pentru Cl

2. CO2 - 1 atom de C si 2 atomi de O

1 mol C..........................6,022*10^23 atomi
1mol..............................6,022*10^23atomi

1mol O2.......................6,022*10^23atomi
2mol...........................x=Calc...

3. 6H2O - 6*2=12 atomi H si 6 atomi O

1mol H2.......................2NA=2*6,022*10^23 atomi
6mol...................................x=calc...

1mol O2.........................2NA=2*6,022*10^23 atomi
6mol.....................................x=calc

4. 2P2O5 - 4 atomi P si 10 atomi O

1 mol P.......................6,022*10^23 atomi
2mol............................x=

1mol O2.................2NA=2*6,022*10^23 atomi
2mol..............................x=

5. 3NaOH -> 3 atomi de fiecare

1mol Na.....................6,022*10^23 atomi
3mol............................x1=x2=x3=

f) 5H2SO4 -> 10 atomi H2, 5 atomi S, 20 atomi O

1mol H2.......................2NA=2*6,022*10^23 atomi
5mol H2.............................x=

1mol S........................6,022*10^23 atomi
5mol...........................x=

1mol O2..........................2NA=2*6,022*10^23 atomi
5mol......................................x=

II. a) MHCl=AH+ACl=1+35,5=36,5g/mol

b) MCO2=AC+2AO=12+2*16=44g/mol

c) H2O=2AH+AO=2*1+16=18g/mol

d) P2O5=2AP+5AO=2*31+5*16=142g/mol

e) MNaOH=ANa+AO+AH=23+16+1=40g/mol

f) H2SO4=2AH+AS+4AO=2*1+32+4*16=98g/mol

1. n=4 moli HCl ---> m=n*M=4*36,5=146g HCl

3. n=6mol H2O -> n=m/M==>m=n*M=6*18=108g H2O

4. n=2 moli P2O5 ---> m=2*142=284g P2O5

5. 3 moli NaOH --> m=3*40=120g NaOH

6. n=5 moli H2SO4 -> m=5*98=490g H2SO4