A 125 ml sample of gas is at STP how many moles of gas are in the sample

5.58*10⁻³ moles of gas are in the sample.

Explanation:

The STP conditions refer to the standard temperature and pressure. Pressure values at 1 atmosphere and temperature at 0 ° C are used and are reference values for gases. And in these conditions 1 mole of any gas occupies an approximate volume of 22.4 liters.

Being 1000 mL equivalent to 1 L, then 125 mL is equal to 0.125 L. Then you can apply the following rule of three: if by STP conditions 22.4 L are occupied by 1 mole, 0.125 L are occupied by how many moles?

aomunt of moles= 5.58*10⁻³ moles

5.58*10⁻³ moles of gas are in the sample.

  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-