Astudent performs an experiment to determine the volume of hydrogen gas produced when a given mass of magnesium reacts with excess hcl(aq) , as represented by the net ionic equation above. the student begins with a 0.0360 g sample of pure magnesium and a solution of 2.0 m hcl(aq).

(a) calculate the number of moles of magnesium in the 0.0360 g sample

1.48x10⁻³ mol

Explanation:

The balanced equation is

Mg(s) + 2HCl(aq) → MgCl₂(aq) + H₂(g)

The aqueous solution will disociate, so:

Mg(s) + 2H⁺(aq) + 2Cl⁻(aq) → Mg²⁺(aq) + 2Cl⁻(aq) + H₂(g)

Simplifying by eliminating the bolded substances that have the same amount in both sides, we have the net ionic equation:

Mg(s) + 2H⁺(aq) → Mg²⁺(aq) + H₂(g).

a) The number of moles of Magnesium is the mass divided by the molar mass (24.305 g/mol):

n = 0.0360/24.305

n = 1.48x10⁻³ mol

  the   balanced   equation   for   reaction of   ca metal   with   o2 to   produce   cao   is as below

2 ca+ o2→ 2 cao2

  explanation

the reaction is   balanced     since the   number of atoms   in reactant side is   equal to   number of atoms   in   product side.   for   example   they   are 2   atom of   ca in   reactant   side   and   2   atoms of ca   in   the product side.

  the   process   is a   meet the   requirement   of   redox   reaction because :     calcium   is   oxidized   from   oxidation state 0   to 2+   while   oxygen   is reduced from   oxidation   state   0   to 2-