Question

WO3(s) + 3H2(g) -> W(s) + 3H2O(g)

Look at the reaction above. Use the rules to assign oxidation numbers to each element in the reaction. Choose the 4 statements below that are TRUE of the reaction.

Answer 1

a
The oxidation number of Tungsten (W) increases.
b
The oxidation number of Tungsten (W) decreases.
c
The oxidation number of Hydrogen (H) decreases.
d
The oxidation number of Hydrogen (H) increases.
e
Tungsten undergoes oxidation.
f
Tungsten undergoes reduction.
g
Hydrogen undergoes oxidation.
h
Hydrogen undergoes reduction.

Answer 2

1. The oxidation number of W in WO3(s) is +6.
2. The oxidation number of H in H2(g) is 0.
3. The oxidation number of O in WO3(s) is -2.
4. The oxidation number of H in H2O(g) is +1.

Answer 3

a) True - The oxidation number of W in WO3 (WO3 -> W) changes from +6 to 0, indicating an increase in oxidation number.
b) False - The oxidation number of W in WO3 (WO3 -> W) changes from +6 to 0, indicating an increase, not a decrease, in oxidation number.
c) False - The oxidation number of H in H2 (H2 -> 3H2O) changes from 0 to +1, indicating an increase, not a decrease, in oxidation number.
d) True - The oxidation number of H in H2 (H2 -> 3H2O) changes from 0 to +1, indicating an increase in oxidation number.
e) True - The oxidation number of W in WO3 (WO3 -> W) increases from +6 to 0, indicating that tungsten undergoes oxidation.
f) False - The oxidation number of W in WO3 (WO3 -> W) increases from +6 to 0, indicating that tungsten undergoes reduction, not oxidation.
g) False - The oxidation number of H in H2 (H2 -> 3H2O) changes from 0 to +1, indicating an increase in oxidation number, not oxidation.
h) True - The oxidation number of H in H2 (H2 -> 3H2O) changes from 0 to +1, indicating an increase in oxidation number, not reduction.