Questions:
- Can either red or blue litmus paper be used to indentify acids? Explain.
Yes, either red or blue litmus paper can be used to identify acid. Acid will turn litmus paper into red color.
- How accurate are indicators for measuring pH?
pH indicator is really accurate in measuring pH. Once the pH paper had been soaked into the chemical, we can compare the colors into the pH indicator chart to determined the pH level of the substance. However, if it’s universal indicator, it has different changes of color, determining how stong the acid/base is.
- What signs of change were observed when acids were placed on metals?
When we mix acid with metal, we will get salt + hydrogen. There are some air bubbles in the test tube. When magnesium ribbon was reacted with hydrochloric acid, bubbles were produced and over time, the magnesium dissolved.
- Did all metals react similarly? Explain how each metal reacted with each acid.
No, each metals has different reaction towards acids. Magnesium react almost immeidately, producing bubbles and eventually dissolved. Zinc gave away air bubbles and absorbed some of the acid, turning the metal powder more dense. The acid reacted with zinc also remains clear, and the zinc did not dissolve. Iron gave nothing away when it react with acid. There were small bubbles here and there, but it didn’t show any physical changes. Like zinc, copper produced occasional air bubbles and absorbed some of the acid so it was more dense. Copper didn’t dissolve and the acid stays clear.
| Properties | Acid | Bases |
| Litmus paper | Turns litmus paper to red | Turns litmus paper to blue |
| pH | Has pH below 7 | Has pH above 7 |
| Corrosive & irritant | Corrosive | |
| Taste sour (not necessarily, but citric acid and acetic acid do) | Soapy | |
| Produces hydrogen and metal salt | All alkali are bases but not all bases are alkali, only the one that dissolved with water |
Chemistry 