Multiple Choice
What is the oxidation state of manganese (Mn) in the compound Mn(CrO4)2?
105
views
6. Chemical Quantities & Aqueous Reactions
Calculate Oxidation Numbers
Multiple Choice
Which choice correctly identifies the oxidation number (o.n.) of sulfur in the compound Na2SO4?
A
+4
B
+6
C
-2
D
0
Verified step by step guidance1
Recall that the oxidation number (o.n.) of sodium (Na) in compounds is always +1 because it is an alkali metal.
Recognize that the sulfate ion (SO4) has an overall charge of -2, so the sum of the oxidation numbers of sulfur and oxygen in SO4 must equal -2.
Know that oxygen almost always has an oxidation number of -2 in compounds (except in peroxides or when bonded to fluorine). Since there are 4 oxygen atoms, their total contribution to the charge is 4 × (-2) = -8.
Set up the equation for the sum of oxidation numbers in the sulfate ion: let the oxidation number of sulfur be x, then x + (-8) = -2.
Solve the equation for x: x = -2 + 8, which gives the oxidation number of sulfur in Na2SO4.
Related Videos
Related Practice
