When she placed her hand on the side of the container, it felt really cold, but it didn't feel that way before. The temperature had dropped by about 30 degrees Celsius. The substance was now grey and crystallin in structure. Was this a chemical reaction?
Answer the question (in a complete sentence) Provide evidence to support your claim and describe (reasoning/justify) how the evidence supports the claim.

Modern pennies are composed of zinc coated with copper. a student determines the mass of a penny to be 2.482 g and then makes several scratches in the copper coaling (to expose the underlying zinc). the student puts the scratched penny in hydrochloric acid, where the following reaction occurs between the zinc and the hcl (the copper remains undissolved): zn(s) + 2 hcl(aq) → h2(g) + zncl(aq)the student collects the hydrogen produced over water at 25 °c. the collected gas occupies a volume of 0.899 l at a total pressure of 79 j mmhg. calculate the percent zinc (by mass) in the penny. (assume that all the zn in the penny dissolves.)