Question

home work chapter 1. please read the question carefully before submitting your answers. questions with a numeric answer should be rounded to the correct significant figures. good luck. question 1 point. classify each of the following changes as physical or chemical: dissolving of sugar in water, condensation of steam, burning of gasoline, souring of milk, melting of gold.

Explanation:

1. Dissolving sugar in water: It's a physical change as no new substance is formed, just a mixture of sugar and water. The sugar molecules disperse in water but retain their chemical identity.
2. Condensation of steam: This is a physical change. Steam (water vapor) changes to liquid water. There is no change in the chemical composition of water, just a change in its physical state from gas to liquid.
3. Burning of gasoline: It is a chemical change. Gasoline reacts with oxygen in the air to produce carbon - dioxide, water, and other by - products. New substances are formed in this reaction.
4. Souring of milk: This is a chemical change. Microorganisms in the milk cause a chemical reaction that changes the composition of milk, producing lactic acid and other substances that give it a sour taste and smell.
5. Melting of gold: A physical change. Gold changes from a solid to a liquid state, but its chemical properties remain the same.

Answer:

1. Dissolving of sugar in water: Physical
2. Condensation of steam: Physical
3. Burning of gasoline: Chemical
4. Souring of milk: Chemical
5. Melting of gold: Physical