Science: Physical or Chemical Change

Physical or Chemical Change 

こんにちは! Today in Science we are conducting a practical experiment around heating a Zinc Oxide and find out whether it is a Physical or Chemical change.

Hypothesis: My hypothesis is that it will be a Chemical change because it absorbs heat, changes its substance, and is not easily reversible. Heat, Sparks, = Chemical. However, I may end up being wrong.

Equipment:

- Sample of ZnO (Zinc Oxide)

- Heat Source

- Scales

- Heatproof container - Evaporating dish

- Tongs

- Heatproof mat

Method: 

1.) Get a sample of Zno in an evaporating dish (about 3 scoops).

2.) Weigh the Zno + container - record weight.

3) Heat container + Zno on a hot plate.

4.) Observe any changes - use the phone for before and after photos

5.) Take off heat + put on a heatproof mat.

6.) Let cool and observe.

7.) Reweigh

Results: 

After doing the experiment, it turns out that heating Zno didn't change its' substance to liquid and there was barely any change. The only visible change was the change of color from White to Light green. The weight of the object was still the same before and after.

Weighs of the ZnO sample:

Before heating: 36g

After heating: 36g

Conclusion:

In conclusion, I was wrong. It was not a Chemical change. It was a physical change because it was easily reversible to its original color when cooled down. There was no new substance formed and the mass of the object was still the same before and after.