Question

Hydrogenperoxide is used as a cleaning agent in the treatment of cuts andabrasions for several reasons. It is an oxidizing agent that candirectly kill many microorganisms; it decomposes upon contact withblood, releasing elemental oxygen gas (which inhibits the growth ofanaerobic microorganisms); and it foams upon contact with blood,which provides a cleansing action. In the laboratory, smallquantities of hydrogen peroxide can be prepared by the action of anacid on an alkaline earth metal peroxide, such as strontiumperoxide.

SrO₂(s) + 2HCl(aq) ?H₂O₂(aq) + SrCl₂(aq)

What amount of hydrogen peroxide should result when 2.40 g ofstrontium peroxide is treated with 23.8 mL of hydrochloric acidsolution containing 0.0400 g ofHCl per mL?
g

What mass of which reagent is left unreacted?
mass
g

reagent

SrO₂HCl