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Questions and Answers
What are the metric or SI units used in measurements of volume?
What are the metric or SI units used in measurements of volume?
liter (L)
What is the metric unit for length?
What is the metric unit for length?
meter (m)
What is the metric unit for mass?
What is the metric unit for mass?
kilogram (kg)
What is the metric unit for temperature?
What is the metric unit for temperature?
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What is the metric unit for time?
What is the metric unit for time?
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How do you identify a number as measured or exact?
How do you identify a number as measured or exact?
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What are significant figures?
What are significant figures?
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What is a metric equality?
What is a metric equality?
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What is the purpose of writing conversion factors?
What is the purpose of writing conversion factors?
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What is density?
What is density?
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How can matter be classified?
How can matter be classified?
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What are the states of matter?
What are the states of matter?
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What are potential and kinetic energy?
What are potential and kinetic energy?
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What is specific heat?
What is specific heat?
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What are the changes of state in matter?
What are the changes of state in matter?
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Study Notes
Units of Measurement
- Key metric/SI units include:
- Volume: liter (L)
- Length: meter (m)
- Mass: kilogram (kg)
- Temperature: kelvin (K)
- Time: second (s)
Measured Numbers and Significant Figures
- Measured numbers are obtained through measurement; exact numbers result from counting or defined quantities.
- Significant figures indicate the precision of a number; rules for counting significant figures include:
- Non-zero digits are always significant.
- Leading zeros are not significant.
- Captive zeros (between non-zero digits) are significant.
- Trailing zeros in a decimal number are significant.
Significant Figures in Calculation
- The result of a calculation should reflect the least number of significant figures from the values used.
- Rounding rules:
- If the digit after the last significant figure is less than 5, round down.
- If it is 5 or more, round up.
Prefixes and Equalities
- Metric prefixes denote multiples or fractions of a unit, allowing conversion in scientific calculations. For example:
- kilo- (k) = 10³
- centi- (c) = 10⁻²
Writing Conversion Factors
- Conversion factors facilitate changing between units; examples include:
- 1 inch = 2.54 cm
- 1 liter = 1,000 mL
Problem Solving Using Unit Conversion
- Dimensional analysis utilizes conversion factors to change units systematically in calculations. Ensure units cancel appropriately for accurate results.
Density
- Density (D) is calculated as mass (m) divided by volume (V): D = m/V.
- Knowing the density allows for determination of mass or volume when either is unknown.
Classification of Matter
- Matter is categorized as:
- Pure substances: elements (unique types of atoms) and compounds (combinations of elements).
- Mixtures: can be homogeneous (uniform composition) or heterogeneous (distinct, separate components).
States and Properties of Matter
- States of matter include solid, liquid, and gas, each exhibiting unique properties.
- Chemical properties pertain to the ability of a substance to undergo a chemical change, while physical properties can be observed without changing the substance.
Temperature
- Temperature conversions can be done among Celsius, Fahrenheit, and Kelvin. Conversion formulas include:
- °C to °F: F = (C × 9/5) + 32
- °C to K: K = °C + 273.15
Energy
- Energy exists in two main forms: potential energy (stored energy) and kinetic energy (energy of motion).
- Conversion of energy units may be required, such as joules to calories.
Energy and Nutrition
- Nutritional energy is measured in kilocalories (kcal) or kilojoules (kJ); caloric content can be calculated based on food composition.
Specific Heat
- Specific heat refers to the amount of heat required to change a unit mass of a substance by one degree Celsius.
- Analyze heat loss or gain during processes like heating or cooling using specific heat values.
Changes of State
- Changes of state include:
- Melting: solid to liquid
- Freezing: liquid to solid
- Vaporization: liquid to gas
- Condensation: gas to liquid
- Sublimation: solid to gas
- Deposition: gas to solid
- Heating and cooling curves illustrate temperature changes during phase transitions without calculations involving heat of fusion or vaporization.
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Description
This quiz covers key concepts from Chapters 2 and 3 of CHEM 1303, focusing on units of measurement, significant figures, and related methodologies in chemistry. Test your understanding of the metric and SI units used in scientific measurements.
