ustal masę cząsteczkową kwasu mlekowego C2H4OHCOOH

mC2H4OHCOOH=2*12u+4*1u+16+1+12+16+16+1=24+5+17+12+32=90u

2*mC + 4*mH + mO + mH + mC + 2*mO + mH=24u + 4u + 16u + 1u + 12u +32u + 1u= 90u

mC2H4OHCOOH=mC*3+mH*6+mO*3=12u*3+1u*6+16u*3=48u+6u+48u=90u