Text A Chemistry 2.2 Properties Of Substances

Question 1

What is the abbreviation for solid state?

Answer 1

(s)

Solid state refers to substances that maintain a fixed shape and volume.

Question 2

What is the abbreviation for liquid state?

Answer 2

(l)

Liquid state refers to substances that have a definite volume but take the shape of their container.

Question 3

What is the abbreviation for gas state?

Answer 3

(g)

Gas state refers to substances that neither have a definite shape nor a definite volume.

Question 4

What is the abbreviation for aqueous state?

Answer 4

(aq)

Aqueous state refers to substances that are dissolved in water.

Question 5

What are some examples of substances in solid state at room temperature?

Answer 5

• iron: Fe (s)
• sodium chloride: NaCl (s)
• octane (found in gasoline): C8H18 (l)

These examples illustrate the solid state of various substances.

Question 6

What are some examples of substances in gas state at room temperature?

Answer 6

• helium: He (g)
• nitrogen: N2 (g)

These examples illustrate the gas state of various substances.

Question 7

What is a key property of ionic compounds such as sodium chloride?

Answer 7

High melting point

Sodium chloride has a melting point of 801°C, characteristic of ionic compounds.

Question 8

How do ionic compounds behave in solid and solution states regarding electrical conductivity?

Answer 8

• Conduct electricity in solution
• Do not conduct electricity in solid state

This behavior is typical for ionic compounds, demonstrating their conductive properties when dissolved.

Question 9

What is the structure of ionic compounds in solid state?

Answer 9

Regular crystalline shapes with flat sides

This indicates that the ions are arranged in a regular, repeating pattern known as a crystal lattice.

Question 10

Fill in the blank: A valid theory must explain _______.

Answer 10

observations

The ability to explain observations is a critical aspect of scientific theories.

Question 11

What physical properties can chemists observe to infer the structure and bonding of substances?

Answer 11

• Structure
• Melting points
• Boiling points
• Electrical conductivity

These properties provide important clues about the nature of bonding in compounds.

Question 12

True or False: The properties of substances remain the same regardless of their state.

Answer 12

False

Substances exhibit different properties in different states, such as solid, liquid, and gas.

Question 13

What is a characteristic melting point of ionic compounds?

Answer 13

Fairly high melting points

This suggests strong attraction between positively and negatively charged ions in the lattice.

Question 14

What does the inability of solid ionic compounds to conduct electricity suggest?

Answer 14

Ions in the lattice are not free to move

This indicates that solid ionic compounds do not have mobile charge carriers.

Question 15

What happens to ionic compounds when they are melted or dissolved in water?

Answer 15

They become electrolytes and conduct electricity

Melting and dissolving break down the crystal lattice, allowing ions to move freely.

Question 16

What is a characteristic melting point of most molecular compounds?

Answer 16

Fairly low melting points

This suggests that the attractive forces between molecules are weak.

Question 17

What property of molecular compounds allows them to be heated further once melted?

Answer 17

They do not decompose into other compounds or elements

This indicates that covalent bonds within molecules are strong.

Question 18

Do molecular substances conduct electricity?

Answer 18

They tend to be non-electrolytes and do not conduct electricity

This suggests that molecular substances are not made of ions.

Question 19

What happens to most molecular substances when dissolved in water?

Answer 19

They do not conduct electricity

However, some can form ions when dissolved, allowing for conductivity.

Question 20

How can you determine if a substance is ionic or molecular based on conductivity?

Answer 20

Further tests are needed to confirm conductivity

Conductivity in water does not definitively indicate whether a substance is ionic or molecular.

Question 21

What is an example of a molecular compound that does not conduct electricity in solid form?

Answer 21

Glucose

Glucose has a relatively low melting point of 146°C.

Question 22

What state are many molecular compounds, such as sulfur dioxide, in at room temperature?

Answer 22

Gases or liquids

This varies among molecular compounds, with some being solids at room temperature.

Question 23

What do theories of ionic and covalent bonding help to describe?

Answer 23

Different properties of substances

Understanding these theories aids in identifying substances as ionic or molecular based on their properties.

Question 24

What are nicotine-like chemicals being investigated for?

Answer 24

Potentially useful medicinal effects

They may be useful in treating Alzheimer’s disease, Parkinson’s disease, some mental illnesses, and adult ADD.

Question 25

What positive effects do some chemicals related to nicotine have on rats?

Answer 25

Improve memory and learning, protect brain cells from toxins ## Footnote Additionally, some are effective painkillers.

Question 26

What is nicotine described as in terms of its effects?

Answer 26

'Dirty drug' ## Footnote Its negative effects often counteract its possible benefits.

Question 27

What is the known medical use of tobacco products?

Answer 27

None ## Footnote Tobacco products like cigarettes contain a mix of potent chemicals.

Question 28

What harmful effects can pure ethanol cause according to its MSDS?

Answer 28

* Mutations * Damage to unborn children * Skin and lung irritation * Unconsciousness * Liver and nervous system damage ## Footnote Despite these hazards, ethanol solutions are commonly used daily through alcoholic beverages.

Question 29

What is caffeine classified as?

Answer 29

Powerful stimulant ## Footnote Found in coffee, tea, cocoa, and chocolate.

Question 30

What physiological effects does caffeine have?

Answer 30

* Causes more frequent urination * Increases blood pressure by constricting blood vessels ## Footnote Caffeine is not classified as a hazardous substance and its use is not regulated.

Question 31

How is the use of performance-enhancing drugs treated in athletic competitions?

Answer 31

Strictly banned ## Footnote This includes substances like steroids.

Question 32

What is the legal status of psychoactive drugs like cocaine, heroin, and ecstasy?

Answer 32

Illegal ## Footnote Their use and sale are prohibited.

Question 33

What restrictions exist regarding the purchase of alcoholic beverages and cigarettes?

Answer 33

Age restrictions ## Footnote People under a certain age cannot legally purchase these products.

Question 34

What recent trend has been observed regarding smoking in public places?

Answer 34

Bans in many towns and cities ## Footnote This reflects changing societal attitudes towards smoking.

Question 35

Why is knowledge of chemistry important for individuals?

Answer 35

Helps make informed personal decisions about harmful chemicals ## Footnote Understanding chemical properties can guide lifestyle choices.

Question 36

Fill in the blank: Caffeine is a _______ that acts as a diuretic.

Answer 36

stimulant

Question 37

True or False: Caffeine is classified as a hazardous substance.

Answer 37

False ## Footnote Caffeine is widely accepted and its use is not regulated.