Question

DAU COROANA VA ROG

3. Ce masà de acid fosforic contine aceeasi cantitate de fosfor ca si 5 moli P2O5?

4. Care este compozitia procentualã masicá a unui aliaj care contine 125 kg fier, 250 kg cupru, 25 kg carbon si 100 kg de siliciu

Answer 1

Răspuns:

3.

MP2O5=2x31+5x16=142g/mol

m=nxM=5x142=710g P2O5

MH3PO4=3x1+31+4x166=98g/mol

142g.........................2x98g

P2O5 + 3 H2O → 2 H3PO4

710g...........................xg

x=710x2x98/142=980g H3PO4

4.

125kgfier+250kgcurpu+25kg carbon+ 100kg siliciu=500kg aliaj

500kg aliaj.......125kg fier.........250kg cupru........25kg carbon.......100kg siliciu

100kg aliaj...........x%fier..............y%cupru...............z% carbon..............t% siliciu

x=100x125/500=25%Fe

y=250x100/500=50% Cu

z=25x100/500=5%C

t=100x100/500=20%Si

Explicație: