Hướng dẫn giải:

 $HCHO\text{ }+\text{ }4\left[ Ag{{\left( N{{H}_{3}} \right)}_{2}} \right]OH~{{\left( N{{H}_{4}} \right)}_{2}}C{{O}_{3}}+\text{ }4Ag\text{ }+\text{ }6N{{H}_{3}}+\text{ }2{{H}_{2}}O$

x                                         4x                   mol

$C{{H}_{3}}CHO\text{ }+\text{ }2\left[ Ag{{\left( N{{H}_{3}} \right)}_{2}} \right]OH~C{{H}_{3}}COON{{H}_{4}}+\text{ }2Ag\text{ }+\text{ }3N{{H}_{3}}+\text{ }{{H}_{2}}O~~$

y                                                                 2y        mol

Có :

30x + 44y = 10,4 và 4x + 2y = 1

=> x=0,2 và y = 0,1

$%C{{H}_{3}}CHO$= 42,31%