chapter 2
Why does the glass of water weigh less after the pill has dissolved?
Carbon dioxide gas will be generated and released as the anti-acid pill dissolves.
What was Democritus's contribution to atomic theory?
Democritus described the tiny ultimate particle as "atomos" (which means "cannot be cut").
What is the law of multiple proportions?
Different compounds may contain the same elements but may have different ratios of those elements.
All of the following are main points of Dalton's atomic theory except: Atoms of different elements differ in size and mass. All atoms of a specified element are identical. Equal masses of two different compounds should have the same number of atoms. Compounds are formed through distinct whole-number combinations of atoms.
Equal masses of two different compounds should have the same number of atoms.
Describe Lavoisier's contribution to the development of modern chemistry.
Lavoisier is the "father" of modern chemistry. He was the first to carry out a series of experiments in which the masses of reactants and products were carefully recorded. These experiments led Lavoisier to formulate the Law of Conservation of Mass.
Fructose (fruit sugar) is always composed of 40.0% carbon, 53.3% oxygen, and 6.7% hydrogen regardless of the fruit that it comes from. What law does this illustrate?
Law of Definite Proportions.
Why did the idea that matter was continuous (rather than atomic) prevail for so long?
Matter appears continuous, and without experimental chemistry, there is no way to prove that matter is not continuous.
Why is it important to recycle mercury-based fluorescent light bulbs instead of putting them in landfills?
Mercury is toxic and can leach from landfills into groundwater.
According to Dalton's atomic theory, when elements react, their atoms combine in (choose one)
One or more simple whole-number ratios.
A sample of an oxide of tin with the formula SnO consists of 0.742 g of tin and 0.100 g of oxygen. A sample of another oxide of tin consists of 0.555 g of tin and 0.150 g of oxygen. What is the formula of the second oxide?
SnO2
Distinguish between the atomic view and the continuous view of matter.
The Atomic theory assumes that matter is made up of small unit particles that cannot be further subdivided and still be the same kind of matter.
Distinguish between the ancient Greek definition of an element and the modern one.
The Greeks believed that there were four basic elements: earth, air, fire, and water.
An iron nail dissolves in a solution of hydrochloric acid. The nail disappears. Have the iron atoms been destroyed? If so, how? If not, where are they?
The iron atoms have not been destroyed; they are in solution.
In one experiment, 3.06 g hydrogen was allowed to react with an excess of oxygen to form 27.35 g water. In a second experiment, electric current broke down a sample of water into 1.45 g hydrogen and 11.51 g oxygen. Are these results consistent with the law of definite proportions? Show why or why not.
Yes The results are consistent with the Law of Constant Composition.
What is a molecule?
a group of atoms chemically bonded to one another
When Mendeleev arranged the known elements in his periodic table, he did so in increasing order of what?
atomic mass
Complete the sentences that explain how this supports the law of definite proportions. A water is a __________ and all samples of water will have two atoms of hydrogen and one atom of oxygen. The ratio of hydrogen to oxygen atoms in water yields a constant _______volume ratio. Cavendish's development of ___________ methods of establishing the _____________ of atoms in a substance produced results substantiating the law of definite proportions.
compound; 2:1; quantitative; proportions
What discoveries finally refuted the idea?
law of multiple proportions law of definite proportions
If you place a 4.00 g effervescent antacid pill into 125 mL (125 g) of water in a 110 g glass, how much will the glass of water weigh once the antacid pill has dissolved?
less than 239 g
Nitrous oxide (N2O, "laughing gas") contains 28.01 g of nitrogen in every 44.01 g of nitrous oxide. What mass of nitrous oxide can be formed from 56.7 g of nitrogen?
m = 89.1 g
What does the chemical formula CO2 represent?
one carbon and two oxygen atoms
Complete the following sentence explaining what happens to carbon atoms when a diamond is burned, and what happens to oxygen and hydrogen atoms when water is electrolyzed. Dalton's theory states that chemical reactions involve the _______________ of atoms, so the carbon atoms in the diamond will _____________ oxygen atoms to form ______ compound and the hydrogen and oxygen atoms in water will form ___________ combinations when water is electrolyzed.
rearrangement combine with a new different
Lavoisier considered alumina an element. In 1825, the Danish chemist Hans Christian Oersted isolated aluminum metal by reacting aluminum chloride with potassium. Later experiments showed that alumina is formed by reacting aluminum metal with oxygen. What did these experiments include?
Aluminum can not be broken down further, it was an element.
How is Avogadro's number linked with the concept of the mole?
Avogadro's number represents: the number of particles contained in one mole.
What were Boyle's contributions to modern chemistry?
Boyle stated that if a substance could be broken down into simpler substances, it was not an element.
Which of the following pairs can be used to illustrate the law of multiple proportions?
CO and CO2
Outline the main points of Dalton's atomic theory.
- Compounds are formed when atoms of different elements combine in fixed proportions. - A chemical reaction involves a rearrangement of atoms but there is no breaking, destroying, or creating of atoms. - Atoms of a given element are alike. - All matter is composed of atoms.
Give two examples of how green chemistry has helped to reduce the use of cadmium in consumer products.
- Substitution of metal hydrides for cadmium in batteries. - Compounds with lower toxicity now substitute for cadmium pigments in plastics.
When 1.00 g zinc and 0.78 g sulfur are allowed to react, all the zinc is used up, 1.50 g of zinc sulfide (ZnS) is formed, and some unreacted sulfur remains. What is the mass of unreacted sulfur?
0.28 g
When a diamond is burned, the mass that remains is zero. b. When a piece of wood is burned, the leftover ashes weigh less than the wood. Upon further investigation, it is noted that CO2 is vented off from both reactions. With this additional information, state how you can prove the diamond is made of pure carbon and yet the wood is not. 1. The ________, which forms the diamond, has been converted to ___________ and escaped into the atmosphere. 2. The carbon in the ______ is converted to carbon dioxide, but the __________ is not 3. Burning the diamond in an ___________ environment would _____ the carbon dioxide for further analysis.
1. carbon; carbon dioxide 2. wood; residual ash 3. enclosed; trap
Complete the following sentences by applying the main points of Dalton's atomic theory. 1. Dalton's atomic theory states, "no atoms are created or broken apart in a chemical reaction". This is a restatement of the ___________________. When 3 grams of carbon is allowed to react with 8 grams of oxygen, 11 grams of carbon dioxide is formed. 2. One of the statements of Dalton's atomic theory is that "compounds are formed when atoms of different elements combine in fixed proportions". This is a restatement of the _____________________ One of the statements of Dalton's atomic theory is that "compounds are formed when atoms of different elements combine in fixed proportions". This is a restatement of the law of definite proportions, but may also explain the __________________.
1. law of conservation of mass 2. law of definite proportions 3. law of multiple proportions
Two compounds, V and W, are composed only of hydrogen and carbon. Compound V is 80.0% carbon by mass and 20.0% hydrogen by mass. Compound W is 83.3% carbon by mass and 16.7% hydrogen by mass. What is the ratio of masses of hydrogen in these compounds given a fixed mass of carbon?
1.00:1.25
Use the figure to calculate the mass of mercuric oxide that would be needed to produce 100.0 g of mercury metal.
107.98g
During a chemical reaction, 25.0 g of propane burns with 90.7 g of oxygen to form carbon dioxide and water. What mass of carbon dioxide and water is formed?
115.7 g
How much does a mole of diatomic fluorine (F2 ) weigh? Express your answer in grams to four significant figures.
32.00 g
What is the mass of helium relative to carbon-12? What is the mass of helium relative to carbon?
4.00/12.00 4.00/12.01
How many atoms are in a mole of oxygen atoms?
6.022×10^23 atoms
How many molecules are in a mole of sugar?
6.022×10^23 atoms
When two elements combine to form two different compounds, the mass ratio of the elements in one compound is related to the mass ratio of elements in the other compound by a small whole number. If two elements AA and BB combine to form two compounds ABAB and AB2AB2 then the ratio of the mass of BB to AA in AB2AB2 and the mass of BB to AA in ABAB will be a simple whole number. When carbon is oxidized in a small amount of oxygen, the principle product formed is carbon monoxide (CO) according to the simplified equation O2(g)+2C(s)→CO(g)O2(g)+2C(s)→CO(g) When the oxidation occurs in a higher concentration of oxygen, the principle product formed is carbon dioxide (CO2) O2(g)+C(s)→CO2(g)O2(g)+C(s)→CO2(g) The mass ratio of oxygen to carbon in carbon dioxide (CO2) is twice the mass ratio of oxygen to carbon in carbon monoxide (CO). A: Identify the statements that are correct based on the video. B: Calculate the mass ratio of SS to OO in SO, and then calculate the mass ratio of SS to OO in SO2, given that the mass of SS is approximately 32 gg and the mass of OO is approximately 16 gg. What is the whole number multiple that describes the relationship between the sulfur-to-oxygen mass ratios of each sample? C: Two different compounds are obtained by combining oxygen with nitrogen. The first compound results from combining 53.3 gg of O with 46.7 gg of N, and the second compound results from combining 82.0 g of O and 17.9 gg of N. What is the whole number multiple that describes the relationship between the oxygen-to-nitrogen mass ratios in each sample?
A: - The mass ratio of oxygen to carbon in CO2CO2 is 2.667 for every sample of CO2. - For two compounds of CC and OO, the mass ratio of CC to OO in one compound is a multiple of the mass ratio of CC to OO in the other compound. - The mass ratio of oxygen to carbon in COCO is 1.33 for every sample of CO. B: Whole number multiple = 2
Before the beginning of the 18th century, only a few elements were known. As the discovery of new elements increased during the 1800s, scientists attempted to develop a simple method of arranging the elements to better understand their properties and the properties of their compounds. Though scientists were able to classify elements into broad categories, they struggled to come to a consensus on how to most effectively group the elements. Gradually, they started grouping the elements based on their relative atomic masses. A Russian chemist, Dmitri Mendeleev, published his version of the systematic arrangement of elements in 1869. There were only 63 known elements during his time, and he arranged them in increasing order of their atomic masses. The periodic table is a tabular arrangement of elements according to their chemical properties. Mendeleev's periodic table gained wide acceptance because he accounted for unidentified elements and also grouped the elements with similar chemical properties. In a few cases, he did this despite the order of their atomic masses. Today, the periodic table consists of 118 elements. A: Identify the factors that guided Mendeleev while classifying the elements. B: Mendeleev wrote chemical formulas using superscripts to indicate the number of atoms of each element in the compound. Modern practice is to reserve superscripts for charges, and subscripts denote the number of each element in a chemical formula. For example, we would write N2O, not N^2O, to indicated two nitrogen atoms. Using Mendeleev's table, predict the formula, using subscripts to denote the number of each atom in the formula, for oxides of carbon (C) and aluminum (Al).
A: - grouping of similar elements together - organizing by increasing atomic mass B: Oxide of C, Al = CO2, Al2, O3
Matter is neither created nor destroyed in a chemical reaction. Thus, the mass of the products of a chemical reaction must be equal to the mass of the starting materials. Formally, this concept is called the law of conservation of mass. A: A sample of sodium reacts completely with 213 g of chlorine, forming 351 g 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 15.6 g of carbon were burned in the presence of 58.8 gg of oxygen, 17.2 g of oxygen remained unreacted. What mass of carbon dioxide was produced? Express your answer to three significant figures and include the appropriate units.
A: 138 g B: 57.2 g
A sulfur dioxide molecule is made up of one sulfur atom and two oxygen atoms. A: What is the mass of one mole of sulfur dioxide? Express your answer in grams to four significant figures. B: How many atoms of sulfur are there in one mole of sulfur dioxide? Express your answer in molecules to three significant figures. C: How many atoms of oxygen are there in one mole of sulfur dioxide? Express your answer in molecules to three significant figures.
A: 64.0g B: 6.02×10^23 atoms of sulfur C: 1.20×10^24 atoms of oxygen
What is the mass of carbon in 85.90 gg of propane? Express your answer to four significant figures. What is the mass of carbon in 291 gg of CO2? Complete the sentences that explain the student why her answer is impossible. The mass of C in 85.90g of propane is 70.18g. The mass of C in the CO2 that forms from combustion _____________ exceed 79.4g according to the law of conservation of mass. However, the mass of C in 291g of CO2 as proposed by the student is 79.4g C, which is _________ than was available in the reaction. Therefore, the answer is impossible.
A: 70.18 g B: 79.4 g C: cannot; more
A: Using Döbereiner's triadic relationship, calculate the mass of As based on Mendeleev's values from his periodic table. B: Using Döbereiner's triadic relationship, calculate the mass of AsAs based on values in the modern periodic table.
A: 76.5 amu B: 76.36 amu
A pure diamond is made only of carbon atoms. A: How many moles of carbon are there in a 1.000 g (5.000 carat) diamond? B: From how many atoms of carbon is this diamond composed?
A: 8.326×10^−2moles B: 5.01×10^22atoms
Consider the following macroscopic (visible to the unaided eye) objects: A: Which are best classified as discrete (like Democritus's description of matter)? B: Which are continuous (like Aristotle's description)?
A: people, calculators, books B: cloth, cheese
The smallest building blocks of matter are atoms. All matter in the universe, including you and me, are made of atoms. Atoms are so small that 7.5 trillion carbon atoms could fit on the period at the end of this sentence. A sample of hydrogen, HH, will contain only hydrogen atoms. Similarly, samples of other elements contain only atoms of that element. An atom is composed of even smaller particles such as protons, electrons, and neutrons. Atoms of elements can bond together to form molecules and compounds. For example, an atom of carbon combines with two atoms of oxygen to form a molecule of carbon dioxide, CO2CO2. A molecule is the smallest unit of a compound. Molecules are made up of a group of atoms tightly bonded together. A molecule of an element is made up of the same kind of atoms, such as Cl2Cl2 and a molecule of a compound is made up of different kinds of atoms, such as NH3NH3. Since the molecule is made up of atoms, it can be separated back into its original form—atoms—through chemical means. Molecular formulas use chemical symbols. For example, in a molecule of Cl2Cl2, the first letter is uppercase and the second letter is lowercase. The symbol ClCl represents only one element, which is chlorine, and a subscript 2 represents the number of atoms of chlorine in the molecule. Consider another example, a molecule of ammonia represented as NH3NH3. Since both the elements are written in uppercase, the molecule has two different atoms—one atom of nitrogen and three atoms of hydrogen. A: Classify the following statements as describing atoms, molecules, or both. B: Classify the following as atoms or molecules.
A: Atoms: Smallest unit of an element Molecules: Smallest unit of a compound, Combination of atoms of the same or different elements Both: Smallest unit that can be isolated through physical changes, Divisible by chemical or nuclear means B: Atoms: Br, P Molecules: SO3, CO, H2
In the figure, the blue spheres represent phosphorus atoms, and the red ones represent oxygen atoms. The box labeled "Initial" represents a mixture. A: Which one of the other three boxes (A, B, or C) could not represent that mixture after a chemical reaction occurred? B: Explain
A: C B: The initial mixture starts with 14 oxygen atoms and box C contains 15 oxygen atoms. This cannot occur because of the law of conservation of mass which states matter can not be created or destroyed during a chemical change. Submit
Applying the law of definite proportions According to the law of definite proportions, a chemical compound is made up of elements proportioned in specific ratios. For example, carbon dioxide has the chemical formula CO2. In 1 mol of CO2, there are 12 g of carbon and 32 g of oxygen. The ratio of the mass of carbon to oxygen in CO2 is 12:32, or 3:8. A: A sample of ammonia contains 9.0 g of hydrogen and 42 g of nitrogen. Another sample of the same compound contains 12.0 g of hydrogen. Calculate the amount of nitrogen in the second sample of ammonia. B: Two experiments were conducted:4.125 g of copper(II) oxide, CuO2, was reduced by heating at high pressure with excess hydrogen to yield 3.294 gg of copper Cu.1.179 g of copper Cu was dissolved in nitric acid to yield copper(II) nitrate, which was converted to 1.476 g copper(II) oxide, CuO2, on ignition. Show that the results illustrate the law of definite proportions by calculating the percentage of oxygen in copper(II) oxide in experiments 1 and 2. Express your answers numerically to two decimal places, separated by commas. Do not enter the percent symbol.
A: Mass of nitrogen in the second sample = 56g B: Percentage of oxygen in sample 1, sample 2 = 20.15, 20.12%
As early as 400 B.C., Greek philosophers proposed that matter was made up of particles. During the 1800s, John Dalton linked the idea of atoms with the chemical identity of an element. His atomic theory of matter involved the following postulates. 1. Each element is composed of extremely small particles called atoms. 2. All atoms of a given element are identical to one another in mass and other properties, but the atoms of one element are different from the atoms of other elements. 3. Atoms of an element are not changed into atoms of a different element by chemical reactions; atoms are neither created nor destroyed in chemical reactions. 4. Compounds are formed when atoms of more than one element combine; a given compound always has the same relative number and kind of atoms. Scientists later discovered isotopes, which showed that the second postulate was not entirely true, and nuclear reactions, which showed that the third postulate was not true. A: Which of the following reactions is possible according to Dalton's atomic theory? B: Magnesium oxide decomposes into magnesium and oxygen. If 16.12 g of magnesium oxide decomposes to form 9.72 g of magnesium, what mass of oxygen gas is also released in the reaction?
A: N2+O2→2NO B: 6.40 g
A city has to come up with a plan to dispose of its solid wastes. The solid wastes consist of many different kinds of materials, and the materials are comprised of many different kinds of atoms. The options for disposal include burying the wastes in a landfill, incinerating them, and dumping them at sea. A: Which method, if any, will get rid of the atoms that make up the wastes? B: Which method, if any, will immediately change the chemical form of the wastes?
A: None of the three methods will destroy the atoms. B: Incinerating wastes.
In an experiment illustrated at right, about 15 mL of hydrochloric acid solution was placed in a flask and approximately 3 g of sodium carbonate was put into a balloon. The opening of the balloon was then carefully stretched over the top of the flask, taking care not to allow the sodium carbonate to fall into the acid in the flask. The flask was placed on an electronic balance, and the mass of the flask and its contents was found to be 38.61 g. The sodium carbonate was then slowly shaken into the acid. The balloon began to fill with gas. When the reaction was complete, the mass of the flask and its contents, including the gas in the balloon, was found to be 38.61 g. A: What law does this experiment illustrate? B: Explain
A: The Law of Conservation of Mass B: The Law of Conservation of Mass states that during a chemical reaction, matter is not created or destroyed and that the total mass is always equal to those of the total reactants. This is why the flask and its contests were 38.61 g and when the reaction was complete (sodium carbonate shaken into the acid), nothing was created nor destroyed so the final mass of the flask remained 38.61 g.
Iron forms a number of oxides in nature. A sample of wüstite (FeO) contains 0.561 g of FeFe and 0.161 g O, while samples of hematite and magnetite contain 0.561 g of Fe and 0.241 g O and 3.37 g Fe and 1.29 g O, respectively. A: Given what we know about wüstite, what are the iron-to-oxygen ratios for hematite and magnetite? B: Do your conclusions agree with the law of multiple proportions? Explain your answer. To convert the values for hematite and magnetite to whole numbers, we multiply the ratios by ______ and _______, respectively. Therefore, the formulas for wüstite, hematite, and magnetite are ________, __________, and ___________, respectively. This is ______________ with the law of multiple proportions.
A: hematite: 0.430 : 0.287; magnetite: 0.382 : 0.287 B: 2, 3, FeO, Fe2O3, Fe3O4, in agreement
