General Chemistry Prelim Quiz

Questions and Answers

What should be the eye level position relative to the meniscus when reading the volume of a liquid in a graduated cylinder?

Below the meniscus

Above the meniscus

At the bottom of the meniscus

At eye level with the meniscus (correct)

Which of the following is a source of error when reading volumetric glassware?

Choosing the right container for measurement

Using a thermometer for temperature measurement

Reading the meniscus at an incorrect angle (correct)

Calibrating the balance before measurement

What is the correct way to read the meniscus of an opaque liquid?

In the middle of the meniscus

At the top of the meniscus (correct)

At the side of the graduated cylinder

At the bottom of the meniscus

What is the maximum weight that can be measured using a triple beam balance?

600 grams Signup and view all the answers

Which statement is accurate regarding the use of a triple beam balance?

The second beam reads in 100 g increments. Signup and view all the answers

Before weighing an object on a triple beam balance, what should be checked?

Check if the pans are clean Signup and view all the answers

Which of the following best describes the role of the first beam on a triple beam balance?

Measures up to 10 grams Signup and view all the answers

Which of the following units is used to measure length in the SI system?

Meter Signup and view all the answers

What is a characteristic of a homogeneous mixture?

It is uniform throughout and has no visible differences. Signup and view all the answers

Which example best represents a heterogeneous mixture?

Oil and water mixture Signup and view all the answers

What distinguishes a pure substance from a mixture?

A pure substance has fixed chemical composition. Signup and view all the answers

What is one characteristic of the Meker burner?

It has a wire grid that separates the flame for better heat distribution. Signup and view all the answers

What type of matter is described as having a fixed chemical composition and characteristic properties?

Pure substance Signup and view all the answers

Which of the following is considered a solution?

Alloys of metals Signup and view all the answers

Which statement describes a common misconception about solutions?

Solutions can only exist in liquid form. Signup and view all the answers

What best describes a feature of a heterogeneous mixture?

It may show differences when examined microscopically. Signup and view all the answers

What occurs during a chemical reaction?

One or more new substances are formed. Signup and view all the answers

Which of the following is an example of a physical change?

Melting of wax Signup and view all the answers

Why is a color change not always an indicator of a chemical change?

Color changes can occur without altering the substance's composition. Signup and view all the answers

How do physical and chemical changes differ with respect to energy?

Chemical changes can produce energy while physical changes typically do not. Signup and view all the answers

What is a characteristic of physical changes?

They generally do not involve the formation of new substances. Signup and view all the answers

Which of these statements correctly describes chemical changes?

During a chemical change, one or more new substances are formed. Signup and view all the answers

Which of the following scenarios indicates a physical change?

Ice melting into water Signup and view all the answers

What can be concluded about the energy dynamics of physical changes?

They generally involve no energy transfer. Signup and view all the answers

Which of the following statements correctly describes a physical change?

The object retains its chemical composition regardless of shape changes. Signup and view all the answers

What type of change occurs when ice turns into water?

Physical change Signup and view all the answers

What happens to molecules during an endothermic process?

Molecules experience an increase in speed due to heat addition. Signup and view all the answers

Which example correctly illustrates an exothermic change?

Freezing water. Signup and view all the answers

What occurs as a result of breaking chemical bonds in a reaction?

Energy is released, often increasing the temperature. Signup and view all the answers

Which of the following changes is NOT a change of state?

Burning wood Signup and view all the answers

Which of the following describes the process of sublimation?

Solid to gas without passing through the liquid state. Signup and view all the answers

What is observed during the melting process?

The solid undergoes a change in state to liquid. Signup and view all the answers

What type of chemical reaction occurs when a cold pack is activated?

It absorbs heat from the environment. Signup and view all the answers

What does a change in color often indicate in terms of chemical reactions?

The mixture of two colors without a change in composition. Signup and view all the answers

What is a common result of a chemical decomposition as seen with a rotten egg?

A noticeable odor is produced. Signup and view all the answers

How is a precipitate defined in the context of chemical reactions?

A solid formed inside a solution. Signup and view all the answers

Which of the following describes a characteristic of chemical reactions that can produce noticeable changes?

They can initiate color changes. Signup and view all the answers

Which reaction would likely result in the formation of a precipitate?

Reacting a soluble carbonate with barium. Signup and view all the answers

What is a potential misconception about color changes in chemical reactions?

All color changes indicate a chemical reaction. Signup and view all the answers

What observation suggests that a chemical reaction has occurred, rather than a physical change?

New smells develop after mixing substances. Signup and view all the answers

Study Notes

SI Units and Measurement Devices

mnemonic for SI units: “King Henry Doesn’t Usually Drink Chocolate Milk”
Kilo (K), Hecto (H), Deca (D), Unit (base units), Deci (d), Centi (c), Milli (m)
Measurement tools include:
- Length: meter stick or scale
- Volume: burette, pipette, graduated cylinder, volumetric flask
- Mass: balance
- Temperature: thermometer
Reading volume in graduated cylinders:
- Place on a flat surface and read the meniscus at eye level
- For transparent liquids, read the bottom of the meniscus
- For opaque liquids, read the top; beware of parallax error

Triple Beam Balance

Maximum capacity is 600 grams
First beam: measures up to 10 grams
Second beam: measures up to 500 grams in 100 g increments
Third beam: measures up to 100 grams in 10 g increments
Always check pans for cleanliness and zero the balance before use

Types of Matter

Matter: anything with mass and occupies space, classified into:
- Pure Substance: fixed composition and distinct properties (e.g., oxygen)
- Mixture: combination of two or more substances retaining individual identities

Mixtures

Homogeneous Mixture: uniform composition with no visible boundaries; can be liquids or solids (e.g., air, tap water, alloys)
Heterogeneous Mixture: non-uniform composition that may appear homogeneous at a glance; observable differences under microscopic examination

Changes in Matter

Physical Change:
- Involves minor energy absorption, reversible, no new substance formed
- Examples include freezing, melting, boiling
- Indicators: shape change, color change (often does not imply chemical change), state change (ice to water, etc.)
Chemical Change:
- Involves energy evolution, irreversible, new substances formed
- Indicators include temperature change, color change, noticeable odor, and formation of precipitate
- Examples of reactions: burning food, rusting metals, reactions yielding heat or requiring energy

Thermal Changes in Reactions

Endothermic Process: heat absorbed, causing temperature drop (e.g., melting, vaporization)
Exothermic Process: heat released, causing temperature rise (e.g., freezing, combustion)

Evidence of Chemical Change

Change in Temperature: indicates bond breaking or forming; can lead to heat discharge or absorption.
Change in Color: often signifies a reaction (e.g., rusting metal changing color).
Noticeable Odor: a sign of a reaction, particularly in decomposition (e.g., rotten egg smell).
Formation of Precipitate: solid formation from a liquid solution, different from suspensions.

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Description

Test your knowledge on SI units and measurement devices in chemistry. This quiz covers the essential prefixes and tools for accurate scientific measurements. Prepare to assess your understanding of the fundamental concepts of General Chemistry.