a, \(n_{P_2O_5}=\dfrac{42,6}{142}=0,3\left(mol\right)\)
\(n_{H_2O}=\dfrac{108}{18}=6\left(mol\right)\)
PTHH: P2O5 + 3H2O ---> 2H3PO4
LTL: \(0,3< \dfrac{6}{3}\rightarrow\)H2O dư
Theo pt: \(\left\{{}\begin{matrix}n_{H_3PO_4}=2n_{P_2O_5}=2.0,3=0,6\left(mol\right)\\n_{H_2O\left(pư\right)}=3n_{P_2O_5}=0,3.3=0,9\left(mol\right)\end{matrix}\right.\)
=> Số ptử H3PO4: 0,6.6.1023 = 3,6.1023 (ptử)
=> Số ptử H2O (dư): (6 - 0,9).623 = 30,6.1023 (ptử)
b, Do mY = mX
=> mO2 (sinh ra từ KClO3) = mO2 (pư vs Cu)
=> nO2 (sinh ra từ KClO3) = nO2 (pư vs Cu)
PTHH:
2KClO3 --to--> 2KCl + 3O2
a --------------------------> 1,5a
2Cu + O2 --to--> 2CuO
3a <--- 1,5a
Mà nCu = b (mol)
=> 3a = b