Chem Chap1 The Chemical World

What is the difference between a "LAW" and a "THEORY"?

A scientific "LAW" is a brief statement that summarizes previous observations and can be used to predict the results of future related experiments. The scientific "LAW" does not explain why the observations occur. That is the role of scientific "THEORY".

What is wrong with the statement, "It is just a THEORY"?

A scientific "THEORY" is the best current explanation of a phenomenon that has been validated by years' worth of experiments.

The manufacturer of a particular brand of toothpaste claims that the brand contains "no chemicals." What does the company mean by that statement? Check all that apply.

A) -The "no chemicals" could refer to additives, preservatives, pesticides, or insecticides, which are all groups of chemicals that many consumers do not want present in their products. -The company is using consumer fear of "chemicals" to imply that their product is safe. B) No, because all matter is composed of chemicals.

Classify each statement as an observation, a law, or a theory: a) The star closest to the Earth is moving away from Earth at a high speed. b) A body in motion stays in motion unless acted upon by force c) The universe began as a cosmic explosion called the Big Bang d) A stone dropped from an altitude of 450 m falls to the ground in 9.6 s.

A) Observation B) Law C) Theory D) Observation

The group members were asked some questions and gave the following responses: How curious are you? How good are your quantitative skills? How hard are you willing to work to succeed in chemistry? Group member 1 1 2 3 Group member 2 3 3 2 Group member 3 4 3 3 Group member 4 5 3 4 Group member 5 5 5 3 Group member 6 2 5 4 Group member 7 3 3 5 Group member 8 1 2 5 Group member 9 4 4 4 Group member 10 4 4 4

A) Report the group average for question "How curious are you?". Express your answer using two significant figures. -3.2 B) Report the group average for question "How good are your quantitative skills? ". Express your answer using two significant figures. -3.4 C) Report the group average for question "How good are your quantitative skills? ". Express your answer using two significant figures. -3.4

What do chemists try to do? How do they understand the natural world?

Chemists study the world around us and try and try to explain how it works. By studying the interactions of atoms and molecules, chemists hope to better understand the world around us.

A student prepares several samples of the same gas and measures their mass and volume. The results are tabulated as follows. Formulate a tentative law from the measurements. Chart: Mass of Gas (in grams) 22.5 35.8 70.2 98.5 Chart: Volume of Gas (in L) 1.60 2.55 5.00 7.01

Examination of the data table reveals that when the mass of the gas increases, a corresponding increase in the volume of the gas occurs. Two equivalent ways of expressing this information as a scientific law would be: (1) the mass of a gas is directly proportional to its volume, or (2) the mass to volume ratio of a gas is constant

What is the "ATOMIC THEORY", and who formulated it?

John Dalton proposed his atomic theory, which states that all matter is composed of small, indestructable particles called atoms.

Determine whether each of the following changes is physical or chemical. Drag the appropriate changes to their respective bins.

Physical: Sugar dissolves in hot water. A metal surface becomes dull because of continued abrasion. Chemical: Sugar burns in a pot. A metal surface becomes dull on exposure to air.

Classify each of the following properties as physical or chemical. Sort these properties into the proper categories.

Physical: the temperature at which dry ice sublimes the boiling point of ethyl alcohol the smell of perfume Chemical: the flammability of ethyl alcohol

Rank the following phrases, which describe the scientific method, from starting point to finishing point. Rank from starting point to finishing point.

Starting point making observations planning experiments performing experiments using logic to come to a conclusion Finishing point

Define CHEMISTRY

The science that seeks to understand what matter does by studying what atoms and molecules do.

Explain the "Scientific Method"

The scientific method is a way of approaching a problem that emphasizes making observations, planning experiments, performing experiments, and then using logic to come to a conclusion.

A student measures the volume of a gas sample at several different temperatures. The results are tabulated as follows. Formulate a tentative law from the measurements. Chart: Temperature of Gas (in Kelvin) 298 315 325 335 Chart: Volume of Gas (in L) 4.55 4.81 4.96 5.11

The temperature of a gas is directly proportional to its volume. The temperature-to-volume ratio of a gas is constant.

Conceptual Checkpoint 1.1 Which statement most resembles a scientific theory? a) When the pressure on a sample of oxygen gas is increased 10%, the volume of the gas decreases by 10% b) The volume of a gas is inversely proportional to its pressure. c) A gas is composed of small particles in constant motion d) A gas sample has a mass of 15.8 grams and a volume of 10.5 liters.

(a) Observation (b) Scientific law (c)proposes a model for what a gas is like<--ANSWER (d) Observation

A) You call one of your friends to go to a movie on Friday night. He declines your invitation, stating that he needs to study for his upcoming exam on Monday. He states that he scores higher on a exam when he studies for the exam. Despite your efforts to convince him to go to the movie, he stays at home to study for his exam. You decide to use the scientific method to test the hypothesis that students who study for an exam tend to score higher than students who do not study for an exam. In what order should you conduct the following steps to test your hypothesis? Rank from first to last. To rank items as equivalent, overlap them. B) Which of the following experiment setups would be the best way to test your hypothesis? C) What was the average exam grade for each set of students?

A) First design anexperiment collectdata analyzedata confirm or revisehypothesis Last B) After the exam, give students a survey questioning their study habits and what grade they made on their exam. C) 91,68

Matter is anything that takes up space and has mass. Matter is classified in many different ways, including by its state (solid, liquid, or gas) and by its composition (pure substances or mixtures). A) The blue spheres below represent atoms. What state of matter is depicted by each graphic? B) Classify each type of matter as an element, a compound, a heterogeneous mixture, or a homogeneous mixture. Drag each item to the appropriate bin.

A) Graphic A- solid Graphic B- gas Graphic C- liquid B) Element: boron magnesium silver Compound: sulfur trioxide sugar acetone Heterogeneous mixture: soil apple juice with pulp Homogeneous mixture: salt water hot coffee air

A)A sample of sodium reacts completely with 0.497 kgkg of chlorine, forming 819 gg of sodium chloride. What mass of sodium reacted? Express your answer to three significant figures and include the appropriate units B)When carbon is burned in air, it reacts with oxygen to form carbon dioxide. When 27.6 gg of carbon were burned in the presence of 87.5 gg of oxygen, 13.9 gg of oxygen remained unreacted. What mass of carbon dioxide was produced? Express your answer to one decimal place and include the appropriate units.

A) 322g B) 101.2g

A) Before we begin, let's first establish an understanding of basic terminology. It may be harder than you think to clearly define what is a chemical versus a chemical reaction. To help us better differentiate between closely related terms, review the words listed here. Sort each of the words into the three categories: contains chemicals, chemical reaction, or neither. B) Read the case study and use your knowledge of the scientific method to identify the observation, hypothesis, experiment, and conclusion. Our English springer spaniels like our neighbors' children and could play with them all day. We thought our dogs will never dislike any children they will ever meet. Last month when we took our dogs on a trip, we met some German tourists in a park. The dogs loved playing with the foreign family's children. Our English springer spaniels like all children. C) For the protection of U.S. consumers, the Food and Drug Administration (FDA) closely regulates product labels, requiring manufacturers to list all of the ingredients in a product. On food labels, the ingredients are listed in order of quantity, so you know that there is more of the first ingredient than any other ingredient. For product labels, the quantity of each ingredient may be less important than the actual effect of the ingredient. Therefore, active ingredients are often separated from the inactive ingredients

A) Contains chemicals: avocados vitamin B1 protein granite Chemical reaction: neutralization combustion bleaching photosynthesis Neither: heat sunlight rainbow B) Allowing the dogs to play with the German family's children is the experiment. "Our English springer spaniels like all children" is our conclusion. "Our English springer spaniels like our neighbors' children" is a(n) observation. "Our dogs will never dislike any children they meet" is the hypothesis C) 1. Eucalyptol is the highest concentration active ingredient. 2. According to the label, its purpose in the mouthwash is to fight plaque and gingivitis. 3. Water is the highest concentration inactive ingredient.

Matter has both physical and chemical properties and can undergo physical or chemical changes. Physical properties are those that a substance displays without changing its composition, whereas chemical properties are evident only during a chemical change (also called a chemical reaction). In contrast, when a substance undergoes a physical change, it may change appearance, but not its composition.

A) Physical change: carving plastic freezing of water slicing a mango tearing aluminum foil Chemical change: bleaching skin silver tarnishing burning toast frying an egg B) Physical property: the color of iron wire the smell of ginger the melting point of water the luster of gold jewelry Chemical property: the explosiveness of fireworks the reactivity of zinc with oxygen the flammability of ether

A) A scientific law is a brief statement that describes past observations and predicts future observations. A theory is a deeper explanation of the underlying cause of observations. An example of a scientific law is the law of conservation of mass, which states that matter is neither created nor destroyed in a chemical reaction. Based on what. you know about scientific laws in general, classify the following statements regarding the law of conservation of mass as true or false.Drag each item to the appropriate bin B) An example of a theory is modern atomic theory, which states that all matter is composed of small particles called atoms. Based on what you know about scientific theories in general, classify the following statements regarding modern atomic theory as true or false. Drag each item to the appropriate bin.

A) True: It was developed from past observations. It predicts future observations. It is subject to experimentation and revision. False: It explains why mass is conserved. B) True: It is supported by data. It is subject to experimentation and revision. It is currently accepted as the most plausible explanation for the law of conservation of mass. False: It is the only possible explanation for the law of conservation of mass. It proves the existence of atoms. It is mere speculation.

A)A chemist decomposes several samples of water into hydrogen and oxygen and measures the mass of the hydrogen and the oxygen obtained. The results are tabulated as follows. Samplenumber Grams ofhydrogen Grams ofoxygen 1 1.5 12 2 2 16 3 2.5 20 B)Next, the chemist decomposes several samples of carbon dioxide into carbon and oxygen. The results are tabulated as follows: SampleNumber Grams ofCarbon Grams ofOxygen 1 0.5 1.3 2 1.0 2.7 3 1.5 4.0

A)Water is always made up of one part hydrogen to eight parts oxygen by mass. B) Carbon dioxide is always made of eight parts of oxygen to three parts carbon by mass. C) A compound is always made of atoms of two or more elements combined in a specific mass ratio. D) A compound is made up of a specific ratio of atoms of each element.

Why does soda fizz?

Soda contains carbon dioxide that are forced into a mixture with water molecules because of the increased pressure. Opening the can of soda will release the pressure, which allows the carbon dioxide, to escape from the mixture and form bubbles.

Provide a brief definition for each of the following: observation, law, hypothesis, and theory. Match the words in the left column to the appropriate blanks in the sentences on the right.

Theory - a system of ideas or principles which are a set of generalized provisions. Observation - an organized perception of phenomena with the aim of studying them. Hypothesis - an approval, suggesting evidence. Law - proven statement explaining the objective facts.

A chemist in an imaginary universe does an experiment that attempts to correlate the size of an atom with its chemical reactivity. The results are tabulated as follows. Chart: Size of Atom small medium large Chart: Chemical Reactivity low intermediate high

a) The reactivity of a chemical is proportional to the molecular size. b) Reactivity is due to the momentum of collisions, and because the larger molecules have a greater momentum, they have a greater reactivity. *Remember this problem is for an imaginary universe.

A 58 gg sample of iron reacts with 25 gg of oxygen to form how many grams of iron oxide? Express your answer using two significant figures.

m =83g