1. In the reaction 2Ca(s) + O2(g) → 2CaO(s), which species is oxidized?

Answer 1

Oxidation is the loss of electrons.
Ca is zero on the left and +2 on the right. O is zero on the left and 2 on the right.
Which element (Ca or O) lost electrons?

Answer 2

so the answer is O
and how is Ca zero on the left there is a 2 in front of it?

Answer 3

No, No, No.
The 2 in front of the Ca is a coefficient, not the charge. It is a zero oxidation state because it is a free element. All free elements (those not in a compound) are zero. O2 is zero for the same reason. So Ca goes from zero on the left to 2+ on the right; therefore, it had to lose two electrons to do that which makes Ca oxidized and O2 is reduced.

Answer 4

i understand!!!!!!! thank you so much. you are awesome

Answer 5

Great!