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Questions and Answers
What can be concluded if experiments do not support the original hypothesis?
What can be concluded if experiments do not support the original hypothesis?
Which statement best describes a solid's particle arrangement?
Which statement best describes a solid's particle arrangement?
What is the primary characteristic of a liquid compared to a solid?
What is the primary characteristic of a liquid compared to a solid?
What role do conclusions play in an experiment using the scientific method?
What role do conclusions play in an experiment using the scientific method?
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In the classification of matter, which of the following is an example of a pure substance?
In the classification of matter, which of the following is an example of a pure substance?
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Which of the following activities exemplifies the scientific method?
Which of the following activities exemplifies the scientific method?
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What is an essential characteristic of gases compared to liquids and solids?
What is an essential characteristic of gases compared to liquids and solids?
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Which of the following best represents the definition of a hypothesis?
Which of the following best represents the definition of a hypothesis?
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Which statement correctly describes the properties of gas?
Which statement correctly describes the properties of gas?
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What distinguishes a heterogeneous mixture from a homogeneous mixture?
What distinguishes a heterogeneous mixture from a homogeneous mixture?
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Which statement correctly describes the metric system of measurement?
Which statement correctly describes the metric system of measurement?
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Which of the following represents a physical change?
Which of the following represents a physical change?
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What role do prefixes play in metric units?
What role do prefixes play in metric units?
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Which of the following best defines a compound?
Which of the following best defines a compound?
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Which of the following is true regarding mass and weight?
Which of the following is true regarding mass and weight?
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What is a characteristic of a homogeneous mixture?
What is a characteristic of a homogeneous mixture?
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Which statement about pure substances is accurate?
Which statement about pure substances is accurate?
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In which situation is the measurement termed 'exact'?
In which situation is the measurement termed 'exact'?
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What is the volume of an object with a length of 5 cm, a width of 3 cm, and a height of 2 cm?
What is the volume of an object with a length of 5 cm, a width of 3 cm, and a height of 2 cm?
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What occurs during a chemical change?
What occurs during a chemical change?
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What is the SI unit of volume?
What is the SI unit of volume?
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Which of the following best illustrates the difference between an element and a compound?
Which of the following best illustrates the difference between an element and a compound?
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Which measurement is considered an inexact number?
Which measurement is considered an inexact number?
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What unit is used for measuring smaller masses?
What unit is used for measuring smaller masses?
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Which of the following represents the correct conversion of 1 kilometer to meters?
Which of the following represents the correct conversion of 1 kilometer to meters?
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What distinguishes a mixture from a pure substance?
What distinguishes a mixture from a pure substance?
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Which of the following temperature scales starts at absolute zero?
Which of the following temperature scales starts at absolute zero?
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How many grams are in one kilogram?
How many grams are in one kilogram?
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What is the relationship between liters and milliliters?
What is the relationship between liters and milliliters?
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Which tool is used to measure small volumes accurately?
Which tool is used to measure small volumes accurately?
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How is mass typically measured in the metric system?
How is mass typically measured in the metric system?
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What is the result of multiplying (2.4 x 10^3) by (4.25 x 10^-7)?
What is the result of multiplying (2.4 x 10^3) by (4.25 x 10^-7)?
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How many significant figures are in the measurement 0.000054 m?
How many significant figures are in the measurement 0.000054 m?
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Which of the following numbers has the most significant figures?
Which of the following numbers has the most significant figures?
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When does a zero count as a significant figure according to the rules?
When does a zero count as a significant figure according to the rules?
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What is the correct representation of the number 0.0000000024 in scientific notation?
What is the correct representation of the number 0.0000000024 in scientific notation?
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Which of these numbers has three significant figures?
Which of these numbers has three significant figures?
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What is the correct interpretation of the number 7000. m?
What is the correct interpretation of the number 7000. m?
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Which of the following is a correct statement about significant figures?
Which of the following is a correct statement about significant figures?
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What is the primary function of using the factor-label method in conversions?
What is the primary function of using the factor-label method in conversions?
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When converting 325 mg to grams, which conversion factor should be chosen to cancel the unit 'mg'?
When converting 325 mg to grams, which conversion factor should be chosen to cancel the unit 'mg'?
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In the factor-label method, when setting up a conversion, what ensures the correct cancellation of units?
In the factor-label method, when setting up a conversion, what ensures the correct cancellation of units?
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When converting 130 lb to kg and using 2.21 lb = 1 kg, what is the appropriate setup?
When converting 130 lb to kg and using 2.21 lb = 1 kg, what is the appropriate setup?
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What is the correct answer when converting 325 mg to grams using proper significant figures?
What is the correct answer when converting 325 mg to grams using proper significant figures?
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Why is it important to write the answer with the correct number of significant figures?
Why is it important to write the answer with the correct number of significant figures?
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Which of the following statements is true regarding the use of units in the factor-label method?
Which of the following statements is true regarding the use of units in the factor-label method?
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In the conversion from pounds to kilograms, what mathematical operation is primarily used?
In the conversion from pounds to kilograms, what mathematical operation is primarily used?
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Study Notes
Matter and Measurement
- Chemistry is the study of matter—its composition, properties, and transformations.
- Matter is anything that has mass and takes up space.
- Naturally occurring matter includes cotton, silk, hair, sand, gemstones, and digoxin.
- Synthetic (human-made) matter includes nylon, polyester, styrofoam, ibuprofen, and many antibiotics.
Chemistry and Matter
- Matter is another word for all the substances that make up our world.
- Examples of matter are antacid tablets, water, glass, and air.
Atoms and Matter
- Chemistry is the study of the composition, structure, and properties of matter, and the changes matter undergoes.
- All matter is made up of basic building blocks called atoms.
Chemicals
- Chemicals are substances that have the same composition and properties wherever found.
- Many chemicals are made by chemists and used in everyday products.
- Examples of chemicals commonly found in toothpaste include calcium carbonate, sorbitol, sodium lauryl sulfate, and titanium dioxide.
Chemicals in the Kitchen
- Examples of common chemicals found in kitchens include silicon dioxide (glass), chemically treated water, metal alloys, natural polymers, and natural gas.
Study Check
- Which of the following contains chemicals.
- Only fruit, milk, and breakfast cereal contain chemicals.
1.1 Scientific Method
- The scientific method is a set of general principles that helps describe how a scientist thinks.
- First, observations of nature are made , followed by questions about what is observed. A possible explanation (hypothesis) is proposed. Following this, experiments are conducted to test the hypothesis. Lastly, a conclusion about whether the hypothesis is true or false is drawn from the analysis of the experimental results.
Discovery of Penicillin
- Penicillin is a substance discovered by scientific methods
Using the Scientific Method
- Suppose you are visiting a friend. Upon arrival, you begin to sneeze.
- You observe that your friend has a new cat.
- You ask why you are sneezing and form a hypothesis that you are allergic to cats.
- You visit other friends who have cats to test your hypothesis.
- If you sneeze after leaving the homes with cats, you can conclude that your hypothesis is correct.
- Through observations you may determine that you are allergic to cat hair and dander.
1.2 Matter
- Elements and compounds, atoms and molecules, pure and impure states of matter, physical and chemical properties are all part of the categorization of matter.
States of Matter
- A solid has a definite volume and shape.
- A liquid has a definite volume but takes the shape of its container.
- A gas has neither a definite volume nor a definite shape. They expand to fill the volume and shape of whatever container they are placed in.
Properties of Matter
- A physical change alters the material without changing its composition (e.g., melting ice; or boiling liquid water to steam).
- A chemical change is a chemical reaction that converts one substance into another (e.g., metabolizing an apple for energy; oxygen and hydrogen combining to form water).
Practice Question
- Which is an example of a physical change?
- Polishing tarnished silver; or melting an ice cube in a glass of soda.
States of Matter: Properties of Matter
- Physical properties can be observed or measured without changing the material's composition.
- Examples include boiling point, melting point, solubility, color, and odor.
A Pure Substance
- A pure substance is composed of a single component.
- It has a consistent composition, regardless of sample size or origin.
- It cannot be broken down into other pure substances through a physical change.
Classification of Matter: Element vs. Compound
- An element cannot be broken down into simpler substances by a chemical change.
- A compound is formed by chemically joining two or more elements.
A Mixture
- A mixture is composed of more than one component and can have a varying composition
- it can be separated into components by a physical change
Homogenous Mixture
- A homogeneous mixture has a uniform composition throughout.
- The different parts of the mixture are not visible (e.g., copper and zinc in brass).
Bronze
- Bronze is an alloy (a homogenous mixture). It contains primarily copper and tin.
Heterogeneous Mixture
- A heterogeneous mixture does not have a uniform composition throughout.
- The different parts of the mixture are visible (e.g., water and copper).
- Mixtures like salads or mixed candies are heterogeneous.
Classification of Matter - Recap
- Matter is anything with mass and volume.
- Matter can be classified as pure substances or mixtures.
- Pure substances can be elements or compounds.
- Mixtures can be homogeneous or heterogeneous.
1.3 Measurements
- Measurements are composed of a number and a unit.
- The metric system uses units like meters (length), liters (volume), and grams (mass).
Measurement: The Metric System of Units
- Each type of measurement has a base unit. The prefixes of the unit names indicate if the unit is larger or smaller than the base unit.
Measurement: The Metric System of Units
- Other units are related to the base unit by a power of 10.
- The prefix of the unit name indicates if the unit is larger or smaller than the base unit.
Measurement: Measuring Length
- 1 kilometer = 1,000 meters, 1 millimeter = 0.001 meters, and 1 centimeter = 0.01 meters.
Measurement: Measuring Mass
- Mass is a measure of the amount of matter in an object.
- Weight is the force that matter feels due to gravity.
- 1 kilogram (kg) = 1,000 grams (g), 1 milligram (mg) = 0.001 grams (g).
Measurement: Measuring Volume
- Volume is the amount of space occupied.
- Volume = Length x Width x Height = cm³
- 1 kiloliter (kL) = 1,000 liters (L), 1 milliliter (mL) = 0.001 liters (L)
Significant Figures
- Exact numbers result from counting objects or are a part of a definition (e.g., 10 fingers, 1 m = 100 cm).
- Inexact numbers are from measurements that have some uncertainty (e.g., a length measurement).
Chemistry and Measurement
- Estimate the length of the piece of wood (based on a ruler).
Chemistry and Measurement
- What value best represents the temperature indicated on the thermometer (based on a diagram of a thermometer)?
- Use 4.85°C based on significant figures
1.4 Expressing Numbers
- Scientific and standard (i.e., decimal) notation are for expressing numbers.
Scientific Notation
- Scientific notation is used for very small and large numbers.
- The format is y x 10x.
Significant Figures
- All nonzero digits in a measurement are always significant.
- A zero counts as a significant figure when it's between two nonzero digits, or at the end of the number with a decimal place. A zero at the beginning of the number is not significant
Significant Figures
- Rules for multiplication and division: The answer has the same number of significant figures as the original number with the fewest significant figures.
- Rules for addition and subtraction: The answer has the same number of decimal places as the original number with the fewest decimal places.
1.5 Expressing a Measurement
- Rounding and significant figures are used in measurements.
Measurement: Measuring Volume
- Volume = length x width x height = cm³ = 1mL = 1cm3 = 1cc
- 1.000 liters is equal to 1000 mL
Significant Figures: Rules for Rounding Off Numbers
- If the digit to be dropped is less than five, just drop it and the remaining digits.
- If the digit to be dropped is five or greater, round up the last digit to be retained by adding 1.
Chemistry and Measurements
- Which of the following values best represents the values displayed on a thermometer?
1.6 SI System
- The International System of Units (SI system) is used for a variety of measurements.
- Equivalents between SI and non-SI units and Prefixes used with SI units can be helpful.
- The density calculation is also part of the SI system.
Units of Measurement: Metric and SI
- The chart shows the metric and SI units for length, volume, mass, temperature, and time.
Length: Meter (m), Centimeter (cm)
- The meter is the SI unit of length.
- 1 meter is equal to 100 cm.
- The meter is slightly bigger than a yard.
Volume: Liter (L), Milliliter (mL)
- The liter is the metric unit for volume, and is slightly larger than a quart.
- 1 liter (L) = 1000 milliliters (mL).
- 1 L = 1.06 qt, 946 mL = 1 qt
Mass: Gram (g), Kilogram (kg)
- The kilogram (kg) is the SI unit of mass.
- 1 kg = 1000 g, 1 kg = 2.2 lb, and 454 g= = 1 lb. The gram (g) is the metric unit of mass, used for smaller masses.
Temperature: Celsius (°C), Kelvin (K)
- Temperature is expressed as Celsius (°C) in the metric system and Kelvin (K) in the SI system.
- Water freezes at 0°C and boils at 100°C.
Time: Second (s)
- The second (s) is the SI and metric unit of time.
Study Check
- What are the SI units for volume, mass, length, and temperature?
Solution
- SI units for volume are cubic meters (m³).
- SI unit for mass is the kilogram (kg).
- SI unit for length is the meter (m).
- SI unit for temperature is Kelvin (K).
Temperature
- Temperature is a measure of kinetic energy
Temperature (Conversion Factors)
- Three temperature scales are used: degrees Fahrenheit (°F), degrees Celsius (°C), and Kelvin (K).
- Conversion formulas are needed to convert from one scale to another.
Temperature: Comparing the Three Temperature Scales
- Shows the different scales for Fahrenheit, Celsius, and Kelvin. These scales are used to compare and measure temperature
Temperature: A Comparison of Temperatures
- A table shows a comparison of temperatures in Fahrenheit, Celsius, and Kelvin for various examples.
Temperature Conversion
- To convert a given temperature in Celsius (°C) into Fahrenheit (°F), the formula °F = 1.8(°C) + 32 can be used.
Temperature
- The temperature in France is 31°C
Density
- Density is the ratio of mass to volume.
- Density = mass/volume
Density
- An average human brain has a capacity of 1.24 L and a mass of 1.30 kg; what is the density of the average human brain?
- The density of the average human brain is 1.05 kg/L
Density
- One thing that does not influence density is amount of substance present.
- Properties that are not influenced by the amount of substance present are called intrinsic properties (e.g. color, boiling point, melting point).
Extrinsic Properties
- Properties influenced by the amount of substance present are called extrinsic properties; (e.g. mass, volume, solubility).
Why does ice float on water?
- The less dense substance will float on top of the denser substance.
Density of Solids
- The density of a solid can be determined by dividing the mass of the object by its volume.
Density Using Volume Displacement
- Find the volume by subtracting the initial liquid volume from the final liquid volume.
Study Check
- What is the density of a 48.0-g metal sample if the liquid in a graduated cylinder rises from 25.0 ml to 33.0 ml?
- The density is 6.0 g/mL
1.7 Converting Units
- Conversion factors are used in converting between units (e.g., converting from lbs to kg). These conversion factors have to be applied in a proper way to obtain the correct units and significant figures.
Problem Solving Using the Factor Label Method: Conversion Factors
- A conversion factor is something that converts a given unit of measurement to another unit of measurement.
- Conversion factors are used in different calculations that require conversions like converting from grams to kilograms.
Using the Factor-Label Method
- The factor-label method is a way to solve problems using conversion factors.
- The method is used to convert from one unit to another unit of measurement.
Using the Factor-Label Method
- Method for solving problems using conversion factors to convert from one unit of measurement to another.
- Make sure that all undesired units cancel out and only the desired unit is left.
Using the Factor-Label Method
- This method is helpful to solve problems by setting up a calculation with the given original measurements and desired units to solve for missing units (like converting from mg to g).
Using the Factor-Label Method
- Identify the original quantity and the desired quantity.
- Write out the conversion factors needed to solve the problem, and choose the appropriate conversion factor needed to solve problems
- Set up the problem; solve the problem, and write the answer with the correct number of significant figures.
Using the Factor-Label Method
- For problems requiring multiple conversion factors, arrange successive factors so the units in the denominator of one factor cancel the units in the numerator of the preceding factor.
Density (a conversion factor)
- Density is a physical property that relates the mass of a substance to its volume, an expression of how much matter is compacted into a given space (measured by mass/volume).
- To convert volume (mL) to mass (g): g/mL x mL = g
- To convert mass (g) to volume (mL): mL/g x g = mL (The inverse of density is used to find volume when given mass )
Density: Solving Problems with Density
- Density is used as a conversion factor to solve problems.
Density
- What is the mass in grams of 85.32 ml of blood plasma with a density of 1.03 g/ml?
- The mass is 87.9 g
Table 2.8 Densities of Some Common Substances
- Table showing the densities of various common substances (solids, liquids, or gases).
Density and Specific Gravity
- Specific gravity compares density of a substance with the density of water at the same temperature.
- Specific gravity is unitless (density (substance)/ density (water) = specific gravity)
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Description
Test your understanding of scientific concepts with this quiz covering hypotheses, the states of matter, and the scientific method. Each question will challenge your grasp on foundational scientific principles and definitions. Perfect for students studying physical science.
