Chem Sem A Six Week Exam Study Unit 1

What is the difference between a hypothesis and a theory?

- Scientific terminology often has precise meanings that differ from everyday language. Example: Acceleration: - In everyday language, "acceleration" refers to speeding up. In science, "acceleration" can encompass slowing down, speeding up, or changing direction. - In science, a "hypothesis" is a prediction or guess based on evidence or observation. - It requires a logical reason for why something is expected to happen or not. - Non-scientists often view "theory" as equivalent to a mere guess. - In the scientific community, a "theory" is a hypothesis accepted as true after repeated testing with consistent results. - Scientific theories remain open to modification based on new data or experimentation. Example: Atomic Theory: - The atomic theory, explaining the composition of the universe, has been modified as new data emerged. - Scientists accept it due to substantial evidence but remain open to refining their understanding.

What is Science?

- a systematic process that follows established rules and procedures. - Its primary objective is to answer questions about the natural world. - One goal of science is to develop an understanding of the world that can be continuously improved and updated. - This refinement happens as we accumulate more knowledge and conduct further experiments. - offers highly probable explanations for natural phenomena. - It does not prove theories to be absolutely correct. - cannot provide absolute proof of any theory. - It can only offer explanations based on observations that are subject to testing and potential revision.

What are the Limitations of Science?

- limited to studying the natural world and its phenomena. - cannot address questions related to beliefs, aesthetics (subjective judgments of beauty), or opinions because they lack empirical testing. - does not prove or establish absolute facts. - New data can potentially disprove existing explanations. - explanations should avoid absolute terms such as "true," "always," or "never" because they do not align with the probabilistic nature of science. - A single experiment can render a current scientific explanation or theory obsolete, highlighting the dynamic and evolving nature of science. - does not make moral or aesthetic judgments. - It cannot determine how knowledge should be used or test opinions about the supernatural (e.g., God, aliens, ghosts).

Aristotle

-Lived in the 4th century B.C. -Renowned Greek philosopher. -Contributions to Science: -Credited with laying the foundation for science. -Aristotle's Explanation for Falling Objects: -Constructed an explanation for falling objects based on his observations. -Believed that falling objects behave according to their nature. Example: Smoke rises because its nature is closer to air's nature, while a rock falls because its nature is closer to earth's nature. Long-Lasting Belief: -Aristotle's conclusions were widely accepted for nearly 2,000 years. The Unresolved Problem: -Despite the seeming reasonableness of Aristotle's explanation, it was never tested or experimentally verified.

What is the correct standard notation for 4.5 x 10-4? 45,000 45 0.00045 0.000045

0.00045

How would you record the following number in standard notation with only two significant figures: ________ 7.4 x 10^-2

0.074

What is 0.80136 expressed with four significant figures? 0.801 0.8014 0.800 0.80136

0.8014

Significant Figures

1) Counting numbers/defined quantities have infinite sig figs. Ex. I have two dogs at home, so I could report that as either "2" or "2.0000000." Either way, it is a defined quantity. I have two dogs. 2) Measurement Non-zero numbers are always significant. Zeros are significant when: they are between significant figures (ex. 304) they are to the right of a significant figure AND after a decimal (ex. 3040.0)

The best glassware to use for mixing, heating, or containing a solution would be a _________.

Beaker

MSDS

Blue Diamond - Health Hazard 4 Deadly 3 Extreme Danger 2 Hazardous 1 Slightly Hazardous 0 Normal Material Red Diamond - Fire Hazard 4 Below 73F 3 Below 100F 2 Above 100F not exceeding 200F 1 Above 200F 0 Will Not Burn Yellow Diamond - Reactivity 4 May Detonate 3 Shock and Heat May Detonate 2 Violent Chemical Charge 1 Unstable if Heated 0 Stable White - Specific Hazard OX Oxidizer ACID Acid COR Corrosive ￦ Use No Water ☢️ Radioactive

Based on the given information, determine if the data are accurate and precise, given an actual true value of 10.9mL? Trial A Volume (mL) 1 11.0 2 10.9 3 11.1 4 10.8 Both accurate and precise Accurare only Precise only Neither accurate nor precise

Both accurate and precise

Which of the following is not a reason why units of measurement were standardized? Units need to be Reliable Units need to be Consistent Units need to be Fair Units need to be Experimental

Units need to be Experimental (Measurement were standardized so the resulting values would be fair, reliable, and consistant. Also, so the results of the experiment could be easily repeatable by other scientists or researchers.)

In order to properly dilute a concentrated acid, you should always add _____ to ______, not the other way around.

When diluting an acid, or a strong chemical, you should always pour the acid into the water, not the other way around.

According to the following MSDS label, which is true about the following substance? (Red-4 Blue-3 Yellow-2 White-W with line through it) a) cannot mix well with water b) will only ignite at very high temperatures c) can safely withstand high pressures d) caries minimal health risk if exposed

a) Cannot mix well with water

Which tool would be used to most accurately measure the volume for a liquid? a) Graduated cylinder b) Beaker c) Erlenmyer Flask D) Cup

a) Graduated Cylinder

Which of the following units are not paired correctly? a) Liter (L) - Mass b) Newton (N) - Force c) Pascal (P) - Pressure d) Joule (J) - Work

a) Liter (L) - Mass

All equipment for an experiment should be: a) placed as far away from the edge as conveniently possible b) placed on top of books or other personal items to conserve space c) placed near the edge of the work space so you may reach it easily d) lefft out for someone else to clean

a) Placed as far away from the edge as conveniently possible

Which of the following does this MSDS hazard symbol indicate? (Skull and bones on caution sign) a) Toxic b) Radioactive c) Flammable d) Reactive

a) Toxic

Which safety precaution is not being followed in the picture below? (Scientists holding a substance) a) wearing safety goggles b) wearing a lab coat c) pulling long hair back d) working with another person

a) Wearing safety goggles

Which best defines a scientific theory? a) a well-established, highly-reliable explanation of a natural event. b) a preliminary guess or idea about an event in nature c) a true statement about an event in nature d) a well-established principle that does not include and explanation

a) a well-established, highly-reliable explanation of a natural event.

A(n) ______________ measurement would be very close to the actual exact value of the measurement.

accurate

When handling hot containers, you must use caution because: a) you will have to pay for anything that breaks b) hot glass and cold glass look the same c) hot containers will scorch the countertops d) chemicals may explode

b) Hot glass and cold glass look the same

Which of the following statements would be the hypothesis most easily tested? a) All organisms are made of cells b) Oak trees grow tallest between temperatures of 10 and 40 degrees Celcius. c) An invertebrate is an animal without a backbone or an internal skeleton d) If life were to exist on another planet, that life would also be composed of carbon compounds.

b) Oak trees grow tallest between temperatures of 10 and 40 degrees Celcius.

Which of the following would you use to rinse chemical spills from your clothing? a) fire blanket b) safety shower c) eyewash station d) first aid kit

b) Safety Shower

The proper method for making an acid solution is a) to slowly add acid to water b) to slowly add water to acid c) to use a large bottle of acid d) to add equal parts of acid and water at the same time

b) To slowly add acid to water

Which of the following statements is the best definition of a scientific hypothesis? a) a suspicion or hunch about an event in nature b) a proposal that can be tested in an experiment c) an idea or explanation that most people agree with d) a well-supported explanation for a broad set of observations

b) a proposal that can be tested in an experiment

Long hair should be tied back when working in a lab because a) it is in style b) it could catch on fire c) It looks neater d) you will stay cooler

b) it could catch on fire

Suppose you were to read about a scientific statement based on data from hundreds of years of research and observation that applies to a broad set of naturally occurring events. Would you consider it a hypothesis or a theory? a) hypothesis b) theory c) both d) neither

b) theory

Which of the following would be a plausible next move if a scientist's repeated experiments did not support his hypothesis? a) Tamper with the experimental results so that the hypothesis was supported. b) Change the scientific hypothesis into a theory. c) Change the hypothesis and conduct a new experiment d) Keep repeating the experiment until the hypothesis is supported.

c) Change the hypothesis and conduct a new experiment

Which of these hypothesis would be most easily tested? a) Green, healthy plants are the most attractive. b) If the weather is cold, people feel more sick. c) If acetic acid is added to a mold colony, the colony will be reduced in size. d) Every plant cell has a cell wall, while every animal cell lacks a cell wall.

c) If acetic acid is added to a mold colony, the colony will be reduced in size.

Why can a scientific hypothesis never be completely proven true? a) A scientific hypothesis is inaccurate. b) Supporting evidence is difficult to find c) New evidence might become available that contradicts a scientific hypothesis. d) It is impossible to design an experiment that can directly test a scientific hypothesis.

c) New evidence might become available that contradicts a scientific hypothesis.

Which of the following is NOT a good lab practice? a) clean up work area during and after lab procedure b) read and understand the lab prcedures before beginning the lab c) once heated, leave chemicals to go to the restroom d) wear goggles at all times during the experiment

c) Once heated, leave chemicals to go to the restroom

Which of the following does not represent a limitation of science? a) Science cannot resolve questions of meaning. b) Science cannot resolve questions of value. c) Science cannot test observations about the natural world. d) Science cannot prove a theory to be absolute truth.

c) Science cannot test observations about the natural world.

When would an established scientific theory most likely be revised or replaced? a) When one scientist argues against a theory b) When general public opinion disagrees with the theory c) When new information is gathered that does not support the current theory. d) When the theory is promoted into a law.

c) When new information is gathered that does not support the current theory.

On a MSDS diamond, which of the following reactivity ratings would indicate a substance is unstable if heated? a) Blue Diamond 3 b) Red Diamond 2 c) Yellow Diamond 1 d) Any Diamond 0

c) Yellow Diamond 1

All of the following are good lab techniques EXCEPT: a) when noting the odor of a chemical, waft the vapors towards the nose b) label all containers before filling them with a solution or solid c) when inserting glass tubing into a rubber stopper, lubricate the tubing first d) pour all chemicals down the drain

d) Pour all chemicals down the drain

When heating chemicals, remember to do all of the following EXCEPT: a) point the mouth of the container away from people b) roll up long sleeves c) tie long hair back d) seal the container

d) Seal the container

Which of the following can science be used to investigate? a) values b) opinions c) supernatural beings d) nature

d) nature

The SI unit for length is _______ and for mass is______.

meters, kilograms

It takes _______ new experiment(s) to disprove a currently accepted theory.

one

A positive exponent will shift the decimal to the ______ and a negative exponent will shift the decimal to the _____.

positive to the right, negative to the left

In a lab experiment, you take measurements which are very close to one another. You would say you have __________ measurements.

precise

Which would measure time with the most precision: a stopwatch measuring hundredths of a second or a wristwatch with a second hand? stopwatch wristwatch

stopwatch

Science is based on observations that can be _____________.

tested

In order to properly test the odor of chemicals in the lab, you should use the technique known as ____________.

Never inhale a fume directly from its container. You should always waft fumes in your direction to investigate odor.

When performing an experiment, is it ok to start mixing chemicals randomly to see what will happen? Please answer "yes" or "no".

No

Which of the following statements about science is true? Science is a flexible pursuit of truth. Science can answer almost any question imaginable. Science follows rules and procedures to answer questions. Science is a branch of philosophy interested in proving facts.

Science follows rules and procedures to answer questions. (Science is a process that follows a set of rules or procedures to answer questions about the natural world.)

What happens when a Scientist's original hypothesis is proved incorrect? Theories or conclusions are amended to agree with new data. Their experiments are thrown out and discredited. The scientific community ignores all of their research. The experiment that disproved the hypothesis is ignored and discredited.

Theories or conclusions are amended to agree with new data. (Even when a Scientist's original hypothesis is proven incorrect, something new an valuable is learned. This just means that a new, better informed hypothesis is born, and should be re-tested with a new experiment.)

Which of the following is the primary characteristic that theories have that hypotheses do not? They have been extensively tested and accepted. They are questions or statements that are testable. They are based on observations of the natural world. They are predictions that can be used to form experiments.

They have been extensively tested and accepted. (A hypothesis is a prediction or guess that is based on evidence or observation whereas a theory is a hypothesis that has been accepted as true because it has been tested repeatedly and produced persistant results.)

Goggles should be worn at all times when performing a lab.

True

True or False: A Theory can and should be modified many times as new information comes available.

True

Which of the following is not a characteristic of a good hypothesis? Specific Testable Realistic True

True ( Not all good hypotheses end up being correct.) (A good hypothesis is pecific, testable, and realistic.)

Is the following statement true or false and why: the main goal of Science is to provide an understanding of the world that can be continuously refined and updated as we gain more knowledge. True, because science can be refined or updated once a conclusion is made. False, because science cannot be refined or updated once a conclusion is made. True, because science seeks to find absolute truth. False, because science seeks to find absolute truth.

True, because science can be refined or updated once a conclusion is made. (The main goal of Science is to provide an understanding of the world that can be continuously refinedand updated as we gain more knowledge.)

Which of the following statements can science test? Two story houses heat up faster in direct sunlight compared to one story houses. Two story houses look better from the street than one story houses. Two story houses tend to be haunted more often than one story houses. Living in a two story house makes people feel taller than living in a one story house.

Two story houses heat up faster in direct sunlight compared to one story houses. (Science cannot answer questions about beliefs, aesthics, or opinions because they cannot be tested empirically.)

Solve the following multiplication problem and report your answer using the correct number of significant figures. 147.8 x 23.2 x 7.926

27,200

How many significant figures are in the following number: 0.0105

3 significant figures 0.0105

How many pounds (lbs) are in 48oz? 2.0 lbs 3.0 lbs 4.0 lbs 4 lbs

3.0 lbs

CHALLENGE: How many years old are you if you have lived one billion seconds? (a billion = 1,000,000,000). Please record your answer to two significant figures. 0.32 years 320 years 3.2 years 32 years

32 years

How many significant figures are in the following number: 403.1 4 3 2

4

How would you record the following number in standard notation with only two significant figures: ________ 7.7847 x 10^4

78,000

Subtract 134.87g from 214g and report with the correct number of significant figures.

79

Which of the following hazards would you watch out for if you noticed the following label on a substance: (chemicals being poured on hands) Radioactivity Toxicity Corrosiveness Flammability

Corrosiveness

The MSDS is included with all chemical shipments and describes the safety precautions and proper disposal of the chemicals. MSDS stands for _________________.

MSDS stands for Material Safety Data Sheet.

Which of the following is not a step in the scientific process? Report the results Make a product based on your conclusion Formulate and Test the Hypothesis Make an observation or question

Make a product based on your conclusion (1. Make an observation or pose a question 2. Fourmulate a hypothesis based on your question 3. Create a conclusion 4. Report results)

Scientific Method

Make an Observation of the Question Formulate a Hypothesis Test the Hypothesis Make a conclusion Report the results (These steps do not always have to be followed in a certain order.)

True or False: A measurement cannot be both precise and accurrate.

False

True or False: It is permissible to wear sandals in the lab area as long as you aren't handling any glassware.

False

True or false: A substance with the following hazard label can be disposed of down the sink drain as long as it is diluted with plenty of water.

False

Galileo

Galileo in the 16th and 17th Centuries: - A prominent figure during the 16th and 17th centuries. Uniform Falling of Objects: - believed that all objects fell uniformly, regardless of their mass or weight. Galileo's Testing Approach: - Unlike Aristotle, Galileo tested his ideas through experiments. Leaning Tower of Pisa Experiment: - reportedly dropped two cannon balls of different masses from the Leaning Tower of Pisa in Italy. - Observed that both objects fell at the same rate and hit the ground simultaneously. Paradigm Shift: - His experiment challenged long-held beliefs about how objects fell. Impact and Repetition of the Experiment: - Variations of Galileo's experiment have been conducted numerous times, both on Earth and in space (Hammer and Feather experiment). - These experiments have contributed to the expansion and refinement of research on falling objects and gravity.