Question

Which of the following chemical equations adhere to the law of conservation
of mass? Copy and balance those that do not.
(a) H2(g) + O2(g) → H2O(g)
(b) 2 NaOH(aq) + Cu(ClO3)2(aq) → Cu(OH)2(s) + 2 NaClO3(aq)
(c) Pb(s) + AgNO3(aq) → Ag(s) + Pb(NO3)2(aq)
(d) 2 NaHCO3(s) → Na2CO3(s) + CO2(g) + H2O(l)

Answer 1

2H2(g) + O2(g) → 2H20(g)
B is balanced
Pb(s) + 2AgNO3(aq) → 2Ag(s) + Pb(NO3)2(aq)
D is also balanced

Answer 2

thank you! for 2NaOH, are there 2 Na and 2 OH ?

Answer 3

Yupp

Answer 4

Numbers before a compound indicates amount of the whole compound, numbers after a molecule indicate the number of those molecules per number of the compound

Answer 5

okay, thanks a lot!