Chapter 1

Question 1

Why is chemistry considered the “central science”?

Answer 1

Chemistry is often called the central science because of its role in connecting the physical sciences, which include chemistry, with the life sciences, pharmaceutical sciences and applied sciences such as medicine and engineering.

Question 2

How is hypothesis defined?

Answer 2

A hypothesis is a proposed explanation for an observation, phenomenon, or scientific problem that can be tested by further investigation.

Question 3

How is scientific law different from scientific theory?

Answer 3

Usually, scientific laws refer to rules for how nature will behave under certain conditions, frequently written as an equation. Scientific theories are more overarching explanations of how nature works and why it exhibits certain characteristics.

Question 4

What are the three domains of chemistry?

Answer 4

Chemists study and describe the behavior of matter and energy in three different domains: macroscopic, microscopic, and symbolic. These domains provide different ways of considering and describing chemical behavior.

Question 5

How does the scientific method work?

Answer 5

The six steps of the scientific method include 1) asking a question about something you observe, 2) doing background research to learn what is already known about the topic, 3) constructing a hypothesis, 4) experimenting to test the hypothesis, 5) analyzing the data from the experiment and drawing conclusions, and 6) communicating the results to others.

Question 6

What are the four states of matter? What are the characteristics of each?

Answer 6

A solid has a definite shape and volume. A liquid has a definite volume but takes the shape of its container. A gas lacks either a defined shape or volume. Plasma is similar to a gas in that its particles are very far apart, but gas is electrically neutral and plasma has a charge.

Question 7

How are mass and weight defined, and how do they relate to each other?

Answer 7

Mass is the total amount of matter, or “stuff,” in an object. Weight is the force of gravity on an object. Mass always stays the same, but weight can change depending on how much gravity is acting upon an object.

Question 8

What is the Law of Conservation of Matter?

Answer 8

The law of conservation of matter states that matter cannot be created or destroyed. It also says that the amount of matter stays the same, even when matter changes form.

Question 9

What types of pure substances are there?

Answer 9

Pure substances can be divided into two categories, elements and compounds.

Question 10

How are elements related to compounds?

Answer 10

When elements combine, they form new substances called compounds.

Question 11

What are the two types of mixtures?

Answer 11

There are two types of mixtures: heterogeneous and homogeneous. Heterogeneous mixtures have visually distinguishable components, while homogeneous mixtures appear uniform throughout.

Question 12

What is the difference between a physical and chemical property?

Answer 12

Chemical properties are properties that can be observed or measured when a substance undergoes a chemical change. Physical properties are properties that can be observed without bringing a chemical change.

Question 13

What is the difference between intensive and extensive properties? What are some examples of each?

Answer 13

Extensive properties vary with the amount of the substance and include mass, weight, and volume. Intensive properties, in contrast, do not depend on the amount of the substance; they include colour, melting point, boiling point, electrical conductivity, and physical state at a given temperature.

Question 14

Why is scientific notation useful? How do we write numbers in scientific notation?

Answer 14

Scientific notation is often used in the fields of science and math. Instead of writing a number in standard form with many zeros, mathematicians and scientists often prefer to condense numbers into scientific notation because it is much more compact. For example, the number 4,000,000,000,000 can be written as 4×10^12

Question 15

What are the standard units in the SI system?

Answer 15

The seven base units in the SI system are:
Length: Meter (m)
Time: Second (s)
Amount of substance: Mole (mol)
Electric current: Ampere (A)
Temperature: Kelvin (K)
Luminous intensity: Candela (cd)
Mass: Kilogram (kg)

Question 16

What are the unit prefixes and how do we use them appropriately?

Answer 16

kilo- k- 1000
hecto- h- 100
deka- d- 10
meter- m- 1
deci- dm- 0.1
centi- cm- 0.01
milli- mm- 0.001

Question 17

What is a derived unit?

Answer 17

A derived unit is a unit that results from a mathematical combination of SI base units.

Question 18

What measurements are necessary to calculate the density of an object?

Answer 18

So, to find the density of an object, we merely need to measure its mass, and then its volume, and then divide the mass by the volume.

Question 19

What is the importance of knowing how many significant figures are in a measurement?

Answer 19

Significant Figures. It is important to be honest when reporting a measurement so that it does not appear to be more accurate than the equipment used to make the measurement allows. We can achieve this by controlling the number of digits, or significant figures, used to report the measurement.

Question 20

Which zeroes in a number are significant?

Answer 20

Zeros to the right of the decimal place that are NOT merely place holders are significant; these significant zeros will be to the right of non-zero significant digits. The zero to the left of the decimal place in 20.00cm is also significant since it now falls between significant digits.

Question 21

How many significant figures should be in the answer to a multiplication or division calculation?

Answer 21

When multiplying or dividing two or more numbers, count the significant figures in each of the original numbers. Take the smallest of the numbers of significant figures. The product or quotient will have that minimum number of significant figures.

Question 22

How many significant figures should be in answer to an addition or subtraction calculation?

Answer 22

When adding/subtracting, the answer should have the same number of decimal places as the limiting term. The limiting term is the number with the least decimal places.

Question 23

What is the difference between accuracy and precision?

Answer 23

Accuracy measures how close results are to the true or known value. Precision, on the other hand, measures how close results are to one another.

Question 24

What is dimensional analysis, and how is it useful in calculations?

Answer 24

Simply put, it is the conversion between an amount in one unit to the corresponding amount in a desired unit using various conversion factors.

Question 25

What are the similarities and differences between Fahrenheit, Celsius, and Kelvin temperature scales?

Answer 25

Because the difference between the freezing point of water and the boiling point of water is 100° on both the Celsius and Kelvin scales, the size of a degree Celsius (°C) and a kelvin (K) are precisely the same. In contrast, both a degree Celsius and a kelvin are 9/5 the size of a degree Fahrenheit (°F).

Question 26

km=? m

Answer 26

1 km = 1000 m

Question 27

Density is defined as:

Answer 27

Mass/Volume