Unit 1: Introduction to Chemistry

Question 1

How do scientists differentiate one type of matter from another?

Answer 1

Scientists differentiate one type of matter from another based on the composition and properties of the material.

Question 2

The properties of matter can be divided into two types:

Answer 2

Chemical properties and physical properties

Question 3

What is a chemical property?

Answer 3

Chemical properties describe how matter reacts (or doesn’t react) in the presence of certain conditions or other chemicals, such as acids, bases, water, and oxygen.

Question 4

What is a physical property?

Answer 4

Physical properties can be observed without trying to change the composition of the matter.

Question 5

What are the two kinds of physical properties?

Answer 5

Intensive properties and extensive properties

Question 6

What are intensive physical properties and some examples?

Answer 6

Intensive physical properties include color, density, luster, melting point, and malleability. These characteristics can identify a substance without being dependent on the amount of matter.

Question 7

What are extensive physical properties and some examples?

Answer 7

Extensive physical properties change based on the amount of matter present. Examples include mass, volume, shape, and length.

Question 8

True or False: When matter is subjected to changes in temperature or exposed to other chemicals, it can undergo both physical changes and chemical changes

Answer 8

True

Question 9

True or False: In a physical change, the physical appearance and physical properties of matter can change

Answer 9

True

Question 10

True or False: In a chemical change, the composition of matter changes, leaving you with a different substance

Answer 10

True

Question 11

What is the chemical formula of rust?

Answer 11

Fe₂O₃ (Iron oxide)

Question 12

Why do some scientists consider salt dissolving in water a chemical change and not a physical change? Why is dissolving sugar in water always a physical change?

Answer 12

When NaCl (table salt) is dissolved in water, the ions Na+ and Cl- form. Individual NaCl units do not exist, so some scientists say this is a chemical change. Sugar, on the other hand, never breaks apart and remains C₁₂H₂₂O₁₁, which is why dissolving sugar in water is always a physical change.

Question 13

True or False: Matter can exist as either pure substances or mixtures

Answer 13

True