Question

possible points: 28.57
determine if each observation below provides evidence of a chemical change.
when a clear solution and a yellow solution are mixed, a dark solid forms at the bottom of the beaker.
salt dissolves in water, creating a clear solution.
a sheet of paper is torn into smaller pieces, but it is still paper.
when a piece of magnesium ribbon is placed in hydrochloric acid, bubbles form and the magnesium disappears.
when a small candle burns, it gives off light, heat, and a new odor.
ice cubes melt into liquid water at room temperature.
:: chemical change :: no chemical change

Explanation:

• Chemical Change: Occurs when new substances form. The dark solid precipitate, gas bubbles from magnesium + acid, and new products (carbon dioxide, water) from candle burning all indicate new substances are created.
• No Chemical Change: Only physical state/shape changes occur. Salt dissolving, paper tearing, and ice melting do not produce new substances, just altered form/state of the original material.

Answer:

1. When a clear solution and a yellow solution are mixed, a dark solid forms at the bottom of the beaker. → Chemical Change
2. Salt dissolves in water, creating a clear solution. → No Chemical Change
3. A sheet of paper is torn into smaller pieces, but it is still paper. → No Chemical Change
4. When a piece of magnesium ribbon is placed in hydrochloric acid, bubbles form and the magnesium disappears. → Chemical Change
5. When a small candle burns, it gives off light, heat, and a new odor. → Chemical Change
6. Ice cubes melt into liquid water at room temperature. → No Chemical Change