125 mL of a stock HCl solution was diluted to make 300 mL of a 0.750 mol/L HCl solution. What was the concentration of the original stock solution?

c= 1.8 mol/l

Explanation: amount of substance remains same.

Amount of substance n = c1·V1 = c2·V2 and c1= c2·V2/ V1

Original concentration c1= 300 ml·0.750 mol/l / 125 ml

where is the following

explanation:

2h2o2--> 2h2o + o2

this reaction is of the spontaneous decomposition of hydrogen peroxide down into water and oxygen.

add 2 molecules of hydrogen peroxide and 2 molecules of water. since oxygen is naturally diatomic, the total number of atoms of each element is now the same on both sides of the equation so it is balanced.

this may not be entirely correct but let me know.