Question

what type of VISUAL indication is there that a reaction happened? a. An iron nail rusts: b. A fireworks display on the 4th of July: c. Alka-Seltzer® is dropped into a glass of water: d. Bleach is spilled onto your favorite shirt:

Answer 1

Reaction can be identified if:

- bubble formation

- solid precipitates

- color change

- change in temperature

therefore

a. An iron nail rusts: --> presence of new chemical, since "grey" metal iron forms rusty red oxides. There is reaction

b. A fireworks display on the 4th of July: --> there is color change, also exothermics, i.e. they are "hot" so there is reaction

c. Alka-Seltzer® is dropped into a glass of water: bubble formation implies chemical reaction

d. Bleach is spilled onto your favorite shirt: --> color change, also bleaching is exothermic, so expect temperature change