1A: Basic Concepts of Chemistry

 

Scientific Method

Exercise \(\PageIndex{1}\)

A hypothesis is a _____.

1. concise statement of behavior that is always the same under the same conditions
2. set of quantitative data
3. tentative explanation or predication based upon experimental observations
4. well-tested unifying principle that explains a body of facts
5. mathematical formula that models a pattern of behavior

Answer

3. tentative explanation or predication based upon experimental observations

Exercise \(\PageIndex{2}\)

To ensure integrity in science, experimental results should be ________ and reported in sufficient detail that the experiment can be repeated by others.

Answer

reproducible

 

 

Qualitative Information

Exercise \(\PageIndex{3}\)

Which of the following is an example of qualitative information about a substance?

1. Color of the substance
2. Melting temperature of the substance
3. Mass of the substance
4. Volume of the substance
5. Boiling temperature of the substance

Answer

1. Color of the substance

 

Green Chemistry

Exercise \(\PageIndex{1}\)

Which of the following statements concerning green chemistry is not correct?

1. It is better to prevent waste than to treat or clean up waste after it is formed.
2. Synthetic methods should be designed to use and generate substances that possess little or no toxicity to human health or the environment.
3. Substances used in a chemical process should pose minimal risk for accidents.
4. Raw materials should be renewable whenever technically and economically practical.
5. Chemical syntheses should be done at extremely high temperatures to ensure harmful bacteria are destroyed.

Answer

5. Chemical syntheses should be done at extremely high temperatures to ensure harmful bacteria are destroyed.

Exercise \(\PageIndex{2}\)

Many regulators, environmentalists, and citizens around the world believe that ________ development is required to meet today’s economic and environmental needs while preserving the options for future generations to meet theirs.

Answer

sustainable

 

Mixtures and Pure Substances

Exercise \(\PageIndex{1}\)

What is the main difference between the following pair?

Homogeneous and heterogeneous mixtures

Answer

A homogeneous mixture is one in which, given any part of the mixture, it has the same concentration (amount of matter per volume) as any other part of the whole, like a brewed cup of coffee or a round of cheese. This is not the case for a heterogeneous mixture, which can be represented by a bowl of mixed jelly beans or gravel.

Exercise \(\PageIndex{2}\)

Define whether each of the following is a pure substance or a mixture.

1. salad dressing
2. copper
3. bronze
4. silk
5. ice

Answer

1. mixture
2. pure
3. mixture
4. mixture
5. pure

Exercise \(\PageIndex{3}\)

Define whether each of the following is a pure substance or a mixture.

1. sand
2. magnesium
3. solid potassium iodide (KI)
4. honey

Answer

1. mixture
2. pure
3. pure
4. mixture

 

Name Elements from Symbols

Exercise \(\PageIndex{1}\)

Give the name of each of the following elements:

1. Rb
2. Os
3. Bi
4. As
5. Rn

Answer e

Radon

Answer d

Arsenic

Answer c

Bismuth

Answer b

Osmium

Answer a

Rubidium

Exercise \(\PageIndex{2}\)

Give the name of each of the following elements.

1. Ba
2. Pu
3. Tl
4. Te
5. Ar

Answer e

Argon

Answer d

Tellurium

Answer c

Thallium

Answer b

Plutonium

Answer a

Barium

 

Name Symbols from Elements

Exercise \(\PageIndex{3}\)

Give the symbol for each of the following elements.

1. Francium
2. Uranium
3. Tin
4. Germanium
5. Helium

Answer a

Fr

Answer b

U

Answer c

Sn

Answer d

Ge

Answer e

He

Exercise \(\PageIndex{4}\)

Give the symbol for each of the following elements

1. Molybdenum
2. Strontium
3. Polonium
4. Silicon
5. Xenon

Answer a

Mo

Answer b

Sr

Answer c

Sn

Answer d

Po

Answer e

Xe

 

Vocabulary

Exercise \(\PageIndex{1}\)

An electrically charged atom or group of atoms is a(n) ________.

1. element
2. ion
3. molecule
4. heterogeneous mixture
5. solution

Answer

2. ion

Exercise \(\PageIndex{2}\)

A pure substance composed of two or more different elements is a(n) ________.

1. ion
2. heterogenous mixture
3. chemical compound
4. solid
5. solution

Answer

3. chemical compound

 

Difference Between Elements, Compounds, and Mixtures

Exercise \(\PageIndex{3}\)

In each of the following pairs, decide which is an element and which is a compound.

1. silver or silver chloride
2. carbon or glucose (sugar)
3. Sodium or salt

Answer

1. Silver, element; silver chloride, compound
2. Carbon, element; Glucose (sugar), compound
3. Sodium, element; Salt (NaCl), compound

Exercise \(\PageIndex{4}\)

Which one of the following substances is classified as a chemical compound?

1. Ir
2. He
3. Ho
4. HI
5. In

Answer

4. HI

Exercise \(\PageIndex{5}\)

Which of the following terms best describes ammonia, NH₃?

1. Homogenous Mixture
2. Ion
3. Element
4. Chemical compound
5. Atom

Answer

4. Chemical compound

 

Difference Between Physical and Chemical Properties

Exercise \(\PageIndex{1}\)

Classify each property as physical or chemical.

1. the tendency of ethyl alcohol to burn
2. the shine of silver

Answer

1. chemical property (burning involves breaking and making bonds, so bonds must be broken and made to observe this property)
2. physical property (shininess is a physical property and so can be observed without making or breaking chemical bonds)

Exercise \(\PageIndex{2}\)

Classify each property as physical or chemical.

1. the odor of paint thinner
2. the flammability of propane gas

Answer

1. physical property (odor can be observed without making or breaking chemical bonds)
2. chemical property (burning involves breaking and making bonds, so bonds must be broken and made to observe this property)

Comparison of Physical Properties

Exercise \(\PageIndex{3}\)

Which one of the following statements is not a comparison of physical properties?

1. Potassium reacts with water more quickly than calcium reacts with water.
2. The electrical conductivity of aluminum is greater than copper.
3. The density of copper is less than the density of lead.
4. The solubility of NaCl in hot water is greater than the solubility in cold water.
5. The boiling point of water is greater than the boiling point of ethanol.

Answer

1. Potassium reacts with water more quickly than calcium reacts with water.

Exercise \(\PageIndex{4}\)

All of the following are examples of intensive properties of matter except _____.

1. a boiling point
2. thermal conductivity
3. malleability
4. the amount of energy transferred as heat
5. color

Answer

4. the amount of energy transferred as heat

 

Determining Physical and Chemical Changes

Exercise \(\PageIndex{1}\)

Indicate (C) if chemical change and (P) if physical

1. Burning Leaves
2. Cutting Diamonds
3. Crushing a pencil
4. The salivary amylase enzyme that breaks down food in the mouth

Answer a

C

Answer b

P

Answer c

P

Answer c

C

Exercise \(\PageIndex{2}\)

Indicate (C) if chemical change and (P) if physical

1. A nail rusting
2. Toast burning
3. Water boiling
4. Ice cream melting

Answer a

C

Answer b

C

Answer c

P

Answer d

P

Exercise \(\PageIndex{3}\)

Which of the following is a physical reaction?

1. Shattering Glass with a baseball
2. Corroding Metal
3. Fireworks Exploding
4. Lighting a match
5. Baking a cake

Answer

a. Shattering glass with a baseball.

Exercise \(\PageIndex{4}\)

Which of the following is a physical reaction?

1. Frying an egg
2. Digesting carrots
3. A Macbook falling out of a window
4. Creating ATP in the human body
5. Dropping a fizzy tablet into a glass of water

Answer

c. A Macbook falling out of a window.

Exercise \(\PageIndex{5}\)

Which of the following is a chemical reaction?

1. Freezing liquid Mercury
2. Adding yellow to blue to make green
3. Cutting a piece of paper into two pieces
4. Dropping a sliced orange into a vat of Sodium Hydroxide
5. Filling a balloon with natural air

Answer

d. Dropping a sliced orange into a vat of Sodium Hydroxide

Exercise \(\PageIndex{6}\)

Which of the following is a chemical reaction?

1. Painting a wall blue
2. A bicycle rusting
3. Ice cream melting
4. Scratching a key across a desk
5. Making a sand castle

Answer

b. A bicycle rusting.

 

Energy

Exercise \(\PageIndex{1}\)

The law of ________ states that the total energy of the universe is constant.

Answer

conservation of energy

Exercise \(\PageIndex{2}\)

________ energy is the energy associated with the separation of two electrical charges.

Answer

Electrostatic

Exercise \(\PageIndex{3}\)

Potential energy possessed by water at the top of a waterfall is known as ________ energy.

Answer

gravitational

Exercise \(\PageIndex{4}\)

Which of the following lists contains only forms of kinetic energy?

1. electrostatic, gravitational, and mechanical energy
2. gravitational, mechanical, and electrical energy
3. thermal, acoustic, and mechanical energy
4. chemical, thermal, and acoustic energy
5. gravitational, chemical, and electrostatic energy

Answer

3. thermal, acoustic, and mechanical energy

Exercise \(\PageIndex{5}\)

A battery-operated power tool, such as a cordless drill, converts

1. electrostatic energy to chemical potential energy.
2. mechanical energy to electrostatic energy.
3. thermal energy to mechanical energy.
4. thermal energy to gravitational energy.
5. chemical potential energy to mechanical energy.

Answer

5. chemical potential energy to mechanical energy.

 

Links to Text

1A.1: Chemistry and it's Methods

1A.2: Sustainability and Green Chemistry

1A.3: Classifying Matter

1A.4: Elements

1A.5: Compounds

1A.6: Physical Properties

1A.7: Physical and Chemical Changes

1A.8: Energy: Some Basic Principles