The reaction between copper and dilute hydrochloric acid will not occur. This is because copper is less reactive than hydrogen, which is present in the hydrochloric acid HCl . In a single replacement reaction, a more reactive element can replace a less reactive element in a compound. However, since copper is less reactive than hydrogen, it cannot replace hydrogen in the HCl compound.If the student were to use a more reactive acid, such as nitric acid HNO3 , then a reaction would occur, producing copper nitrate Cu NO3 2 and hydrogen gas H2 . But in the case of dilute hydrochloric acid, no reaction will take place, and no products will be formed.