Properties and Changes of Materials：練習問題

Which of the following describes a chemical change that results in the formation of a new material and is typically irreversible?

Which of the following is a chemical change that is typically irreversible?

Which of the following processes is an example of an irreversible change?

What are the three main states of matter that materials can exist in?

When mixing salt into water, the salt seems to disappear. What is the name of this process, and is it a reversible or irreversible change?

A student has a mixture of sand, salt, and small iron filings. Describe a sequence of three physical methods the student can use to separate these three materials completely.

Properties and Changes of Materials
A student is testing different materials to see which are soluble in water. She adds one teaspoon of the following substances into separate beakers containing 100 ml of water and stirs for two minutes:
1. Salt
2. Sand
3. Sugar
4. Flour
(a) Which of these substances are soluble in water?
(b) Describe how the appearance of the liquid in the beaker containing sand would differ from the one containing salt after stirring.

Properties and Changes of Materials
A student investigates the solubility of three different white powders: sugar, chalk, and salt. They add \(10\)g of each to \(100\)ml of water at \(25^{\circ}C\).

(a) Define the term solute in the context of this experiment.
(b) Which of these powders would form a saturated solution first if the student kept adding more of it? Assume salt is more soluble than sugar but chalk does not dissolve.
(c) If the student heats the water to \(60^{\circ}C\), how will the solubility of the sugar change? Explain why.