Question

Ms. Pitt set up a classroom demonstration to show what happens when a sample of zinc metal is add a.ed to a flask containing hydrochloric acid (HCl). The diagram shows what the students in the classroom observed during the demonstration. The students made two other observations: The flask felt warmer after adding the sample. The sample became smaller over time. Which of the following is NOT an evidence of a chemical reaction in this example.

A. Gas collected in the balloon
B.Temperature of sample is increased
c.Volume of HCl remains the same
D.Size of the zinc has become smaller

Answer 1

Reaction

Zn (s) + 2HCl (aq) ⇒ ZnCl₂ (s) + H₂ (g)

A. gas H₂ collected: true

B. Every chemical reaction produces or absorbs heat. In chemistry, this effect is described as the enthalpy of a reaction.

This reaction releases heat (exothermic) and causes the temperature to increase: true

C. the volume of HCl will decrease because it reacts: false

D. the size of the zinc metal decreases as it reacts: true

Answer 2

volume of HCl remains the same