Unit 1: Basic Concepts of Chemistry Flashcards
What are the dimensions of physical quantities?
mass, length, and time
How are fundamental units represented?
Mass [M], Length [L], Time [T]
A ________________ indicates the contribution of fundamental units to a physical quantity’s units.
dimensional formula
Why are dimensional formulas important?
They provide a systematic method to represent dimensions of physical quantities using fundamental units.
What is a physical quantity in chemistry?
mass, length, time, temperature.
What do dimensional formulas help explain?
They help explain how physical quantities are derived from mass, length, and time.
What does a physical quantity consist of?
Each physical quantity has a numerical value and a unit
_______________ are classified into fundamental units and derived units.
Units
What are fundamental units?
Fundamental units cannot be derived from other units; there are seven recognized fundamental units.
Give an example of a physical quantity and its unit.
Example: Mass - 44 Kilogram.
_______________ is the measure of the extent of a two-dimensional surface.
Area
What is the SI unit and dimensional formula for volume?
SI unit: cubic meter (m³); Dimensional formula: [M^0 L^3 T^0].
How is density calculated and what are its dimensions?
Density = Mass/Volume; Dimensions are [M^0 L^{-3} T^0].
What is the dimensional formula for acceleration?
The dimensional formula for acceleration is [M^0 L T^{-2}].
What is specific gravity and does it have dimensions?
Specific gravity is the ratio of a material’s density to water’s density; it has no dimensions.
Which tool would you use to measure mass?
Balance
What does SI stand for in the context of units?
International System of Units
Which of the following is an example of a fundamental unit?
Meter
What is a physical quantity?
A measurable property of a physical system
Explain the difference between fundamental units and derived units.
Fundamental Units: Basic measurements (e.g., meter, kilogram) that define physical quantities.
Derived Units: Combinations of fundamental units (e.g., Newton, Joule) used to express other measurements.
What are the seven fundamental units in the SI system?
The seven fundamental units in the SI system are:
Meter (length)
Kilogram (mass)
Second (time)
Ampere (electric current)
Kelvin (temperature)
Mole (amount of substance)
Candela (luminous intensity)
Describe the role of units in measuring physical quantities.
Units provide a standard way to quantify physical quantities, allowing for clear communication and comparison. They define the scale and context of measurements, ensuring consistency in scientific calculations and everyday use. Examples include meters for length, kilograms for mass, and seconds for time.
Which tool is most appropriate for measuring the mass of the chemical sample?
Electronic scale
Why is it important to use SI units in measurements?
To maintain consistency and standardization globally
What is the speed of the toy car, and which unit should be used to express this physical quantity?
The speed of the toy car is 2.5 meters per second (m/s), calculated by dividing distance (5 m) by time (2 s).
A physics student is conducting an experiment to measure the speed of a toy car rolling down an incline. She records the distance traveled as 5 meters and the time taken as 2 seconds. She needs to calculate the speed and present it with the appropriate unit.
An example of a physical quantity is force, measured in newtons (N).
A science teacher, Ms. Adams, is conducting a lab experiment with her students to measure various physical quantities. They are using a meter stick for length, an electronic scale for mass, and a graduated cylinder for volume. However, one student mistakenly uses a thermometer to measure the volume of water.
The answer does not address the fundamental error of using a thermometer instead of a graduated cylinder for measuring volume.
A physics student is conducting an experiment measuring the speed of a toy car rolling down a ramp. She notes the distance covered and the time taken to calculate the speed, which she expresses in meters per second (m/s).
Distance divided by time
A physics student is conducting an experiment measuring the speed of a toy car rolling down a ramp. She notes the distance covered and the time taken to calculate the speed, which she expresses in meters per second (m/s).
The unit of speed is meters per second (m/s)
A physics student is conducting an experiment to measure the speed of a moving object. She records the length of the track as 50 meters and the time taken for the object to travel this distance as 10 seconds. What fundamental quantities are used to derive speed?
Length and Time
A physics student is conducting an experiment to measure the speed of a moving object. She records the length of the track as 50 meters and the time taken for the object to travel this distance as 10 seconds.
Which quantity is being calculated in this experiment?
Speed
How is a physical quantity expressed, and what components does it consist of?
A physical quantity is expressed as a combination of:
Magnitude: a numerical value
Unit: a standard measurement (e.g., meters, seconds)
Together, they define the quantity, like “5 meters” or “10 seconds.”
In a physics lab, students are tasked with measuring the mass of various objects. They use an electronic scale for kilograms and a graduated cylinder for volume in liters. The instructor emphasizes the importance of using SI units for consistency across experiments.
Which unit would be used to measure electric current?
Ampere (A)
In a physics lab, students are tasked with measuring the mass of various objects. They use an electronic scale for kilograms and a graduated cylinder for volume in liters. The instructor emphasizes the importance of using SI units for consistency across experiments.
Why is it essential to use SI units in scientific measurements?
To ensure consistency and standardization
Why is labeling containers important in the laboratory?
Labeling ensures clear identification of contents for safety and effective use.
What personal protective equipment is essential in the lab?
Safety glasses must be worn at all times to prevent eye damage.
How should you properly handle glassware like beakers and flasks?
Always hold them from the bottom or side walls for stability and safety.
What should you avoid when handling glassware?
Avoid holding glassware from the topmost side to ensure safety and stability.
What is a critical practice when washing glass pipettes and burettes?
Ensure the ends do not touch the sink to prevent breakage.
What are the minimum PPE requirements in a laboratory?
Lab coat, gloves, eye protection, long pants, and closed-toe shoes are mandatory.
What risks are associated with glassware in laboratories?
Glassware can fracture, leading to injuries and contamination from hazardous materials.
What should you do with cracked or contaminated glassware?
Cracked glassware should be disposed of; contaminated glassware must be cleaned before reuse.
How should broken glassware be disposed of?
It should be discarded in a designated container for glass disposal after removing hazards.
What type of glassware should be used for heating?
Only borosilicate glassware designed for heating or rapid temperature changes should be used.
