Oxidation-Reduction half equations

Question

Hey how would I write the oxidation half equation and the reduction half equation for the following reactions and then the overall(complete) equations.

1) Some chlorine water (aqueous chlorine) is added to a solution of sodium bromide

2) some aluminum foil is left to react overnight in hydrochloric acid solution.

3) A mixture of copper(II) oxide and magnesium is ignited and allowed to burn

also what is the element like hydrogen is H what is iodine vapour? is it I2?

thnx

Answer 1

1) Some chlorine water (aqueous chlorine) is added to a solution of sodium bromide

Cl2  & 2 electron --> 2 Cl- (reduction)

2 Br-  -->   Br2 & 2 electrons (oxidation)

============================

2) some aluminum foil is left to react overnight in hydrochloric acid solution.

Al --> Al+3 & 3 electrons (oxidation)

2 H2O & 2 electrons --> H2 & 2 OH-  (reduction)

==========================

3) A mixture of copper(II) oxide and magnesium is ignited and allowed to burn

CuO  & 2 electrons --> Cu & O-2 (a reduction)

Mg --> Mg+2 & 2 electrons (oxidation)

===================

also what is the element like hydrogen is H

H is the symbol for the element Hydrogen, but since two atoms pair up into a molecule,... H2 is the formula for the element Hydrogen

what is iodine vapour? is it I2?,

yes it is I2,  the solid iodine evaporates (sublimes) directly into fumes of I2 ( they are purple)