Worksheet identifying chemical and physical changes with examples and a molecular diagram.

To solve the problem, we need to identify whether each process listed is a chemical change or a physical change. Here's a breakdown of each item:

Definitions Recap:

- Chemical Change: A chemical reaction occurs, and new products are formed. The identity of the matter changes.
- Physical Change: Matter changes form but its identity does not change.

Analysis of Each Item:

1. Heating water into steam
- Explanation: When water is heated, it changes from a liquid to a gas (steam). This is a change in state but no new substance is formed.
- Type: Physical Change

2. Milk going sour
- Explanation: Milk going sour involves the fermentation of lactose by bacteria, producing lactic acid and other compounds. New substances are formed.
- Type: Chemical Change

3. Dissolving sugar in water
- Explanation: Sugar dissolves in water, forming a solution. No new substance is created; it is just a mixture.
- Type: Physical Change

4. Iron rusting
- Explanation: Rusting is the oxidation of iron, forming iron oxide. A new substance (rust) is formed.
- Type: Chemical Change

5. Hydrochloric acid and sodium hydroxide reacting and forming salt and water
- Explanation: Hydrochloric acid reacts with sodium hydroxide to form sodium chloride (salt) and water. New substances are formed.
- Type: Chemical Change

6. Digesting food into nutrients
- Explanation: Digestion involves breaking down complex molecules into simpler ones (e.g., proteins into amino acids). New substances are formed.
- Type: Chemical Change

7. Melting ice into water
- Explanation: Ice melting into water is a change in state from solid to liquid. No new substance is formed.
- Type: Physical Change

8. Acid rain dripping onto limestone and making carbon dioxide gas
- Explanation: Acid rain reacts with limestone (calcium carbonate), producing calcium ions, water, and carbon dioxide gas. New substances are formed.
- Type: Chemical Change

9. Breaking a glass into pieces
- Explanation: Breaking glass into pieces is a physical alteration in shape but no new substance is formed.
- Type: Physical Change

10. Hydrogen peroxide decomposing into oxygen gas and water
- Explanation: Hydrogen peroxide decomposes into oxygen gas and water. New substances are formed.
- Type: Chemical Change

Final Answer:

\[
\begin{array}{|c|l|c|}
\hline
\text{No.} & \text{Process} & \text{Type} \\
\hline
1 & \text{Heating water into steam} & \text{Physical Change} \\
\hline
2 & \text{Milk going sour} & \text{Chemical Change} \\
\hline
3 & \text{Dissolving sugar in water} & \text{Physical Change} \\
\hline
4 & \text{Iron rusting} & \text{Chemical Change} \\
\hline
5 & \text{Hydrochloric acid and sodium hydroxide reacting and forming salt and water} & \text{Chemical Change} \\
\hline
6 & \text{Digesting food into nutrients} & \text{Chemical Change} \\
\hline
7 & \text{Melting ice into water} & \text{Physical Change} \\
\hline
8 & \text{Acid rain dripping onto limestone and making carbon dioxide gas} & \text{Chemical Change} \\
\hline
9 & \text{Breaking a glass into pieces} & \text{Physical Change} \\
\hline
10 & \text{Hydrogen peroxide decomposing into oxygen gas and water} & \text{Chemical Change} \\
\hline
\end{array}
\]

\boxed{
\begin{array}{|c|l|c|}
\hline
\text{No.} & \text{Process} & \text{Type} \\
\hline
1 & \text{Heating water into steam} & \text{Physical Change} \\
\hline
2 & \text{Milk going sour} & \text{Chemical Change} \\
\hline
3 & \text{Dissolving sugar in water} & \text{Physical Change} \\
\hline
4 & \text{Iron rusting} & \text{Chemical Change} \\
\hline
5 & \text{Hydrochloric acid and sodium hydroxide reacting and forming salt and water} & \text{Chemical Change} \\
\hline
6 & \text{Digesting food into nutrients} & \text{Chemical Change} \\
\hline
7 & \text{Melting ice into water} & \text{Physical Change} \\
\hline
8 & \text{Acid rain dripping onto limestone and making carbon dioxide gas} & \text{Chemical Change} \\
\hline
9 & \text{Breaking a glass into pieces} & \text{Physical Change} \\
\hline
10 & \text{Hydrogen peroxide decomposing into oxygen gas and water} & \text{Chemical Change} \\
\hline
\end{array}
}