Question

1. classify the following changes in matter as a physical change or a chemical change. change physical or chemical? hammering metal into sheets rusting rotting wood heated water changes to steam melting ice salt dissolving in water sodium in water produces h₂ gas shredding paper mixing an acid with a base sublimation melting silver & pouring in a mold

Explanation:

Step1: Recall physical - chemical change definitions

Physical change: No new substances formed, only change in physical state or form. Chemical change: New substances formed with different chemical properties.

Step2: Analyze hammering metal into sheets

Only shape changes, no new substance. So it's a physical change.

Step3: Analyze rusting

Iron reacts with oxygen to form iron oxide (rust), new substance formed. So it's a chemical change.

Step4: Analyze rotting wood

Organic matter decomposes due to biological and chemical processes, new substances formed. So it's a chemical change.

Step5: Analyze heated water changes to steam

Change of state from liquid to gas, no new substance. So it's a physical change.

Step6: Analyze melting ice

Change of state from solid to liquid, no new substance. So it's a physical change.

Step7: Analyze salt dissolving in water

Salt dissociates in water but no new chemical substance is formed. So it's a physical change.

Step8: Analyze sodium in water producing H₂ gas

Sodium reacts with water to form sodium hydroxide and hydrogen gas, new substances formed. So it's a chemical change.

Step9: Analyze shredding paper

Only physical form changes, no new substance. So it's a physical change.

Step10: Analyze mixing an acid with a base

Neutralization reaction occurs, new substances (salt and water) are formed. So it's a chemical change.

Step11: Analyze sublimation

Change of state from solid to gas directly, no new substance. So it's a physical change.

Step12: Analyze melting silver & pouring in a mold

Change of state from solid to liquid and then back to solid, no new substance. So it's a physical change.

Answer:

Hammering metal into sheets: Physical change
Rusting: Chemical change
Rotting wood: Chemical change
Heated water changes to steam: Physical change
Melting Ice: Physical change
Salt dissolving in water: Physical change
Sodium in water produces H₂ gas: Chemical change
Shredding Paper: Physical change
Mixing an acid with a base: Chemical change
Sublimation: Physical change
Melting silver & pouring in a mold: Physical change