Name: how scientists test a hypothesis
Uploaded: 2020-09-03T13:38:25.000Z
Duration: 3 min 50 s
Channel: JoVE

K12 Standards

north-carolina-k-12-science-standard-course-of-study

North Carolina K-12 Science Standard Course of Study

9-12

Chemistry

Matter and its Interactions

PS.Chm.1.1

The Scientific Method

科学的方法は すべての 科学分野で採用されている 体系的なアプローチです 観察や質問 仮説の構築 実験の実施 データの解釈 そして 最後に結論の導出という 6つの主要なステップを 踏んで行うものです 科学的方法は 観察とその観察結果を 理解するための 質問から始まります 例えば フランスの化学者 アントワーヌ・ラヴォワジェは 燃焼現象を観察しました 彼は 何かが燃えると 何が起こるのかを理解するために ある質問を立てました 物質はどこに行くのか？科学的方法の第3のステップは 仮説を立て 問題となっている観察に対する 仮の説明を組み立てます 物質はどこに行くのか？という彼の質問に答えて ラヴォワジエは化学反応では 物質は生成も破壊されてもいない という仮説を立てました 優れた仮説はテスト可能であり また 検証可能です 私見可能な仮説とは 実験や観察によって確認できる 予測を立てるものです 実験によって反論できる仮説は 反証可能な仮説である 科学的方法の第4ステップは 実験とデータ収集です 実験とは 温度や 圧力 体積などの 制御された環境下で行われる 観察や測定のことです このステップでは 現実の世界が仮説によって 予測されたものとどれだけ 適合しているかを調査します 実験や観察には プロセスがどのように起こるかを 記述する定性的なものがあります 他のものは定量的なもので 測定またはプロセスについての 何かを定量化します ラヴォワジエは密閉された設定で 水銀を加熱することによって 彼の仮説をテストしました これは赤みを帯びた 物質の形成につながりました 彼の実験は定量的だったので 彼は慎重に反応物と 生成物の質量を 別々にだけでなく 閉じたシステム内で 記録しました 第5のステップは データの解釈と分析です 結果が仮説を支持するか 反論するかを評価し さらなる実験が 必要かどうかを評価します ラヴォワジェは 反応前と反応後の瓶と その内容物の合計質量が 同じであることを観察しましたが 赤い生成物の質量は 元の水銀よりも大きかったのです 最後のステップは 論理的な結論を導き 仮説を受け入れるか否かを 決めることです 結果が仮説を強く支持する場合 仮説は受け入れられます また 新しい質問をしたり 新しい実験を 行ったりすることで さらに検証を行ったり 洗練されたりすることもあります 彼の実験からは 瓶の全質量が 反応中に変化しなかったので 瓶の中の酸素が水銀と結合して 新しい生成物を形成していたと 結論付けました この物質は 現在は水銀(II)酸化物として 知られています この結論は 物が燃える過程では 物の総質量は変化しないという 質量保存の仮説を 強く支持するものでした しかし 仮説が反証された場合 科学者は失敗した実験を 参考にして新たな仮説を立て 新たな実験を 始めることができます 科学的方法を 一連のステップと見なしていても 新しい情報やアイデアがあれば そのプロセスのどの時点からでも 後戻りしてステップを 繰り返すことに なるかもしれません このように 科学的方法は 繰り返しのプロセスなのです

科学的手法

化学は経験的科学です。 科学者は日常生活で化学を理解するために疑問を投げかけたり、これらの疑問に対する答えを求めたりすることがよくあります。 これを達成するために、科学者は「科学的方法」という一連の明確な手順を実行します。 このアプローチは、観察、疑問、仮説の構築、実験の実施、結果の分析、 そして結論からなります。  
 
 <h4>観察と疑問 </h4>
 
 科学的手法の最初のステップは、物理的な世界で現象を観察することです。 次に、その現象をより理解するための疑問が出ます。 たとえば、「ただの水か、塩が入った水、どちらが速く凍るか」などです。 
 
 <h4>仮説 </h4>
 
 次のステップでは、特定の観察結果に対する説明を作成します。この一連の観察結果に対する暫定的な解釈を仮説と呼び、 観察された現象を理解するための指針となります。 たとえば、上記の質問では、塩を加えると水の凝固点が変化するという仮説があります。 
 
 科学者は、以前の研究や文献を使用して調査を開始し、実験で検証できる仮説を作成することがよくあります。 強力な仮説は、検証可能であり、かつ反証可能です。 正しいと証明できるものが検証可能と見なされ、正しくないと証明できるものが反証可能と見なされます。反証された場合、科学者は仮説を修正または破棄する必要があります。  
 
 <h4>実験  </h4>
 
 3 番目のステップは、仮説の妥当性を検証するための実験を設計し、実施することです。 実験とは、制御された条件下で実施される測定と観測のことです。 観察や実験の中には定性的なもの（プロセスがどう起こるか仕組みを説明するもの）と定量的なもの（プロセスに関する何かを測定または定量化するもの）があります。 海水仮説を検証するために、科学者は同量の水が入った２つのグラスを室温で用意します。 片方のグラスにスプーン１杯の塩を入れて、両方のグラスを冷凍庫に入れておきます。 各グラス内の水の状態は 15 分ごとに観察でき、各グラスの水が完全に凍結するまでの時間を記録します。  
 
 実験のデザインは科学的な方法の重大なステップです。 特定の要因の影響を監視できるように、変動要因の数を制御するように注意する必要があります。  
 
 <h4>結果の分析と結論 </h4>
 
 次のステップは、実験結果を分析し、これらの結果が仮説を実証できるかどうかを結論付けることです。 結論として実証できるのであれば、仮説は受け入れられ、新しい質問に答えるためのさらなる実験が行われる可能性があります。 仮説が間違っていることが証明された場合、新しい仮説を提案し、このプロセスが続きます。  
 
 塩水の例では、結果は塩水が明らかに水より凍るまでに時間がかかるという結果が出ます。 これにより塩分を含んだ水は普通の水より凍る速度が遅いという結論が得られます。 したがって、この結果は仮説を実証するものです。 
 
 このテキストは <a href="https://openstax.org/books/chemistry-2e/pages/1-1-chemistry-in-context">、 Openstax, Chemistry 2e, Section 1.1: The Scientific Method から引用したものです。</a>

化学は経験科学です。科学者は、日常生活の化学を理解し、これらの質問に対する答えを求めるために、しばしば質問を投げかけます。宛先。。。

Education

JoVE Core

化学

Introduction: Matter and Measurement

序論：物質と測定

KEY TERMS AND CONCEPTS

主要用語と概念

how scientists test a hypothesis

Chemistry uses the scientific method to turn observations into testable answers. Scientists begin by observing a phenomenon in the physical world and then asking a question about it. This process helps explain everyday chemistry through evidence.

A question leads to a hypothesis, which is a tentative explanation for what is being observed. Scientists often use earlier research and published literature to shape that idea. A strong hypothesis must be testable, meaning it can be supported by evidence, and falsifiable, meaning it can also be proven wrong.

The next step is experimentation. Scientists design and carry out experiments under controlled conditions to test the hypothesis. These tests can include qualitative observations, which describe how a process happens, and quantitative measurements, which record how much or how long something changes.

A clear example is the freezing of plain water and salt water. A scientist can place equal amounts of room-temperature water into two glasses, add salt to one glass, and put both in a freezer. By checking the glasses every 15 minutes and recording the time until each one freezes, the scientist can compare the results while keeping other variables controlled.

After the experiment, the results are analyzed and used to form a conclusion. If the data support the hypothesis, it may be accepted and tested further with new questions. If the hypothesis is not supported, a new one can be proposed and the process begins again. In the salt-water example, the results show that salt water freezes more slowly than plain water, so the hypothesis is validated.

How Scientists Test a Hypothesis

scientific laws and theories

How Science Explains Laws and Theories

Scientific laws and scientific theories describe science in two different ways. A law is a concise verbal or mathematical statement that summarizes many experimental observations. It describes or predicts aspects of the natural world that stay the same under the same conditions. A scientific theory is different because it explains why natural events happen. It is a unifying principle that gives a well-supported and testable explanation for a broad set of observations. Strong theories are the...

the scientific method

Chemistry uses the scientific method to turn observations into testable answers. Scientists begin by observing a phenomenon in the physical world and then asking a question about it. This process helps explain everyday chemistry through evidence. A question leads to a hypothesis, which is a tentative explanation for what is being observed. Scientists often use earlier research and published literature to shape that idea. A strong hypothesis must be testable, meaning it can be supported by...

physical and chemical properties of matter

physical-and-chemical-properties-of-matter

Distinguishing Physical and Chemical Changes

Matter can be identified by its properties, which are the features that help us tell one substance from another. These properties fall into two main groups: physical properties and chemical properties. Understanding the difference helps explain how matter changes. A physical property is a feature of matter that is not linked to a change in chemical composition. Examples include density, color, hardness, melting point, boiling point, and electrical conductivity. Some physical properties can be...

what is energy?

Energy Forms and Conservation

Energy is a property of matter that appears in many forms. On Earth, most energy starts with the Sun. Plants capture light energy from the Sun and use photosynthesis to turn it into chemical energy. That stored energy can then move through living things and materials in several ways. People get energy from plant foods, and wood or coal, which come from fossilized plants, can be burned to produce heat and electricity. Energy is defined as the ability to do work. Work happens when a force moves...

classifying matter by state

States of Matter and Their Properties

States of matter help describe how matter behaves in chemistry. Matter is anything that has mass and takes up space. It is found everywhere, including air, water, soil, mountains, and even our bodies. The three common states on Earth are solid, liquid, and gas. A solid has a definite shape and a definite volume. Its particles, such as atoms or molecules, are packed very closely together and held in place by strong forces, so they only vibrate slightly. This tight arrangement makes solids...

measurement: standard units

Measurement: SI Units and Conversions

Measurement gives three kinds of information: a number, a unit, and an estimate of uncertainty. The number shows size or magnitude. The unit gives a standard for comparison. The uncertainty reflects possible error in the measurement. Numbers can be written in more than one way. A value may appear in decimal form or in scientific notation, which is also called exponential notation. For example, the maximum take-off weight of a Boeing 777-200ER airliner is 298,000 kilograms, or 2.98 × 10^5 kg. <br...

classifying matter by composition

Matter: Elements, Compounds, and Mixtures

Matter can be grouped by composition into pure substances and mixtures. A pure substance has a constant composition throughout and uniform properties. For example, any sample of sucrose has the same composition and the same physical properties, such as melting point, color, and sweetness, no matter where it is isolated from. A mixture contains two or more kinds of matter in varying amounts. Its parts can be separated by physical changes, such as evaporation. The components keep their own...

measurement: derived units

SI Units, Density, and Property Types

SI units and derived units help describe physical properties in chemistry. The International System of Units, or SI system, uses agreed-upon base units for seven fundamental properties: length, mass, time, temperature, electric current, amount of substance, and luminosity. Units made by combining these base units are called SI-derived units. Speed is one example. If distance is measured in meters and time in seconds, the derived unit for speed is meters per second, or m/s. Miles per hour is...

dimensional analysis

Using Conversion Factors to Cancel Units

Dimensional analysis is a method for using conversion factors to cancel units and solve measurement problems. It is also called the factor label method. The main rule is that units must be treated the same way as the numbers attached to them. A conversion factor is a ratio of two equal quantities written in different units. For example, 1 meter is equal to 1.0936 yards. That relationship can be used to build a factor that converts one unit into the other. When a value is multiplied or divided...

uncertainty in measurement: accuracy and precision

uncertainty-in-measurement-accuracy-and-precision

Measurement Error: Reading Results Correctly

Measurement error affects how scientists judge the quality of their results. Repeated measurements help show whether results are precise and accurate. A measurement is precise when repeated values are very similar. A measurement is accurate when it is very close to the true or accepted value. Precise values agree with each other, while accurate values agree with the true value. A pharmaceutical quality control chemist can use this idea to check machines that dispense 500 mL of cough syrup. The...

uncertainty in measurement: reading instruments

uncertainty-in-measurement-reading-instruments

Measurement Uncertainty and Significant Figures

Measurement uncertainty and significant figures show how carefully a value can be read from an instrument. Counting is different. If the number of objects does not change during counting, the result is exact. Defined quantities are exact too. For example, 1 foot is exactly 12 inches, 1 inch is exactly 2.54 centimeters, and 1 gram is exactly 0.001 kilograms. Most other measurements are not exact because the measuring process has limits. The result depends on the device used and on the person...

uncertainty in measurement: significant figures

uncertainty-in-measurement-significant-figures

Significant Figures and Rounding Rules

Significant figures and rounding rules help students report measurements with the right level of certainty. A measurement includes every digit that was actually measured, including the last uncertain digit. That is why a value can look simple but still carry useful information about the tool used to measure it. Zero can also be significant when it is part of a measured value. For example, if a scale reads 140 pounds to the nearest pound, the 1, 4, and 0 are all significant. Reporting...

key terms and concepts

Explore how scientists use observations, hypotheses, controlled experiments, and data analysis to test ideas, using a salt water freezing example.

How Scientists Test a Hypothesis | JoVE K12

chemistry

JoVE Core 化学は、簡潔で理解しやすいアニメーションビデオレッスンを使用して、一般的な化学の概念を生き生きとしたものにします。さらに、活動する科学者のビデオでは、現在世界中の実験室で行われている古典的そして独創的な研究・実験をお見せします。

Virginia  Standards of Learning

HIgh School

Earth Science

ES.1

ES.1.a

ES.1.f

Life Science

LS.1

LS.1.a

LS.1.f

Physical Science

PS.1

PS.1.f

Physics

PH.1

PH.1.f

Texas Essential Knowledge and Skills

High School

CHEM.1

CHEM.1.A

CHEM.1.H

Florida Department of Education

Nature of Science

SC.912.N.1

SC.912.N.1.1

SC.912.N.1.2

SC.912.N.2

SC.912.N.2.1

PHYS.4

PHYS.4.A

PHYS.4.B

Chemistry and Physics

IPC.4

IPC.4.A

Scientific Laws and Theories

Scientific Laws

In science, a law is defined as a concise, verbal or mathematical, statement that summarizes a vast number of experimental observations. ...

Chemistry is an empirical science. Scientists often pose questions to understand the chemistry in everyday life and seek answers to these questions. To ...

Classifying Matter by State

Chemistry is the study of matter and the changes it undergoes. Matter is anything that has mass and occupies space. Matter is all around us; the air, ...

Classifying Matter by Composition

Matter: Pure Substances and Mixtures
According to its composition, the matter can be classified into two broad categories &mdash; pure substances and ...

The Atomic Theory of Matter

The earliest recorded discussion of the basic structure of matter comes from ancient Greek philosophers. Leucippus and Democritus argued that all matter ...

Subatomic Particles

Dalton was only partially correct about the particles that make up matter. All matter is composed of atoms, and atoms are composed of three smaller ...

Elements: Chemical Symbols and Isotopes

A chemical symbol is an abbreviation used to indicate an element or an atom of an element. For example, the symbol for mercury is Hg. The same symbol is ...

Use models to explain how the scientific understanding of atomic structure has evolved.

Radioactivity and Nuclear Equations

Nuclear chemistry is the study of reactions that involve changes in nuclear structure. The nucleus of an atom is composed of protons and, except for ...

Types of Radioactivity

The most common types of radioactivity are &#945; decay, &#946; decay, &#947; decay, neutron emission, and electron capture.
Alpha (&#945;) decay is the ...

Nuclear Stability

Protons and neutrons, collectively called nucleons, are packed together tightly in a nucleus. With a radius of about 10&#8722;15 meters, a nucleus is ...

Nuclear Binding Energy

The difference between the calculated and experimentally measured masses is known as the mass defect of the atom. In the case of helium-4, the mass defect ...

Radioactive Decay and Radiometric Dating

Radioactivity is a spontaneous disintegration of an unstable nuclide and is a random process, as all the nuclei in the sample do not decay simultaneously. ...

Nuclear Fission

Many heavier elements with smaller binding energies per nucleon can decompose into more stable elements that have intermediate mass numbers and larger ...

Nuclear Power

Controlled nuclear fission reactions are used to generate electricity. Any nuclear reactor that produces power via the fission of uranium or plutonium by ...

Nuclear Fusion

The process of converting very light nuclei into heavier nuclei is also accompanied by the conversion of mass into large amounts of energy, a process ...

Nuclear Transmutation

Nuclear transmutation is the conversion of one nuclide into another. It can occur by the radioactive decay of a nucleus, or the reaction of a nucleus with ...

Use models to compare nuclear reactions including alpha decay, beta decay and gamma decay; nuclear fusion and nuclear fission.

PS.Chm.1.2

Atomic Orbitals

An atomic orbital represents the three-dimensional regions in an atom where an electron has the highest probability to reside. The radial distribution ...

The Pauli Exclusion Principle

The arrangement of electrons in the orbitals of an atom is called its electron configuration. We describe an electron configuration with a symbol that ...

The Energies of Atomic Orbitals

In an atom, the negatively charged electrons are attracted to the positively charged nucleus. In a multielectron atom, electron-electron repulsions are ...

The Aufbau Principle and Hund's Rule

To determine the electron configuration for any particular atom, we can build the structures in the order of atomic numbers. Beginning with hydrogen, and ...

electron-configuration-of-multielectron-atoms

Electron Configuration of Multielectron Atoms

The alkali metal sodium (atomic number 11) has one more electron than the neon atom. This electron must go into the lowest-energy subshell available, the ...

Use models to explain how electrons are distributed in atoms.

PS.Chm.1.3

Periodic Classification of the Elements

The periodic table arranges atoms based on increasing atomic number so that elements with the same chemical properties recur periodically. When their ...

The Periodic Table

As early chemists discovered more elements, they realized that various elements could be grouped by their similar chemical behaviors. One such grouping ...

Atomic Mass

Atoms &mdash; and the protons, neutrons, and electrons that compose them &mdash; are extremely small. For example, a carbon atom weighs less than 2 ...

Molar Mass

The identity of a substance is defined not only by the types of atoms or ions it contains but by the quantity of each type of atom or ion. For example, ...

Use the Periodic Table as a model to predict the relative properties of elements based on the pattern of valence electrons in the outermost energy levels of atoms.

PS.Chm.2.1

atomic-radii-and-effective-nuclear-charge

Atomic Radii and Effective Nuclear Charge

The elements in groups of the periodic table exhibit similar chemical behavior. This similarity occurs because the members of a group have the same number ...

Ionic Radii

Ionic radius is the measure used to describe the size of an ion. A cation always has fewer electrons and the same number of protons as the parent atom; it ...

Ionization Energy

The amount of energy required to remove the most loosely bound electron from a gaseous atom in its ground state is called its first ionization energy ...

Electron Affinity

The electron affinity (EA) is the energy change for adding an electron to a gaseous atom to form an anion (negative ion).



This process can be either ...

Construct an explanation to infer the atomic size, reactivity, electronegativity, and ionization energy of an element based on its position in the Periodic Table.

PS.Chm.2.2

Types of Chemical Bonds

Chemical bonding theories were pioneered by American chemist Gilbert&#xA0;N. Lewis. He developed a model called the Lewis model to explain the type and ...

Lewis Symbols and the Octet Rule

Chemical bonds are complex interactions between two or more atoms or ions, which reduce the potential energy of the molecule. Gilbert N. Lewis developed a ...

Ionic Bonding and Electron Transfer

Ions are atoms or molecules bearing an electrical charge. A cation (a positive ion) forms when a neutral atom loses one or more electrons from its valence ...

The Born-Haber Cycle

Lattice Energy&#xA0;

An ionic compound is stable because of the electrostatic attraction between its positive and negative ions. The lattice energy of a ...

trends-in-lattice-energy-ion-size-and-charge

Trends in Lattice Energy: Ion Size and Charge

An ionic compound is stable because of the electrostatic attraction between its positive and negative ions. The lattice energy of a compound is a measure ...

Covalent Bonding and Lewis Structures

Compared to ionic bonds, which results from the transfer of electrons between metallic and nonmetallic atoms, covalent bonds result from the mutual ...

Electronegativity

Whether a bond is nonpolar or polar covalent is determined by a property of the bonding atoms called electronegativity.&#xA0;

Electronegativity values of ...

bond-polarity-dipole-moment-and-percent-ionic-character

Bond Polarity, Dipole Moment, and Percent Ionic Character

Bond Polarity

The absolute value of the difference in electronegativity (&Delta;EN) of two bonded atoms provides a rough measure of the polarity to be ...

lewis-structures-of-molecular-compounds-and-polyatomic-ions

Lewis Structures of Molecular Compounds and Polyatomic Ions

To draw Lewis structures for complicated molecules and molecular ions, it is helpful to follow a step-by-step procedure as outlined:


	Determine the ...

Resonance

The Lewis structure of a nitrite anion (NO2&minus;) may actually be drawn in two different ways, distinguished by the locations of the N-O and N=O ...

Formal Charges

In some cases, there are seemingly more than one valid Lewis structures for molecules and polyatomic ions. The concept of formal charges can be used to ...

Exceptions to the Octet Rule

Many covalent molecules have central atoms that do not have eight electrons in their Lewis structures. These molecules fall into three categories:


	...

Bond Energies and Bond Lengths

Stable molecules exist because covalent bonds hold the atoms together. The strength of a covalent bond is measured by the energy required to break it, ...

Analyze and interpret data to explain the mechanisms and properties of the two main types of intramolecular (ionic and covalent) bonds.

PS.Chm.3.1

molecular-comparison-of-gases-liquids-and-solids

Molecular Comparison of Gases, Liquids, and Solids

Particles in a solid are tightly packed together (fixed shape) and often arranged in a regular pattern; in a liquid, they are close together with no ...

Construct an explanation to summarize the influences intermolecular forces have on the properties of chemical compounds.

PS.Chm.3.2

Analyze the structure of atoms and isotopes.

How Scientists Test a Hypothesis

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