Question

in a chemical change, a chemical reaction occurs and new products form. energy is either absorbed or released. in a physical change, matter changes form, but its identity is not changed. identify each change as chemical or physical.

change	physical or chemical change?
2. milk going sour
3. dissolving sugar in water
4. iron rusting
5. hydrochloric acid and sodium hydroxide reacting and forming salt and water
6. digesting food into nutrients
7. melting ice into water
8. acid rain dripping onto limestone and making carbon dioxide gas
9. breaking glass into pieces
10. hydrogen peroxide decomposing into oxygen gas and water

Explanation:

Step1: Analyze heating water into steam

Water changes from liquid to gas, but still H₂O. Physical change.

Step2: Analyze milk going sour

Chemical reaction occurs due to bacteria, new substances form. Chemical change.

Step3: Analyze dissolving sugar in water

Sugar disperses in water, no new substance chemically. Physical change.

Step4: Analyze iron rusting

Iron reacts with oxygen to form iron - oxide. Chemical change.

Step5: Analyze HCl and NaOH reaction

Acid - base reaction forms new substances (salt and water). Chemical change.

Step6: Analyze digesting food

Complex chemical reactions break food into nutrients. Chemical change.

Step7: Analyze melting ice into water

Ice changes from solid to liquid, still H₂O. Physical change.

Step8: Analyze acid rain on limestone

Acid - carbonate reaction produces CO₂ and new substances. Chemical change.

Step9: Analyze breaking glass

Glass shape changes, no new chemical substance. Physical change.

Step10: Analyze hydrogen peroxide decomposition

H₂O₂ breaks into O₂ and H₂O. Chemical change.

Answer:

1. Physical change
2. Chemical change
3. Physical change
4. Chemical change
5. Chemical change
6. Chemical change
7. Physical change
8. Chemical change
9. Physical change
10. Chemical change