Chemistry Exam 1 - Ch. 2 HW

Magnesium oxide decomposes into magnesium and oxygen. If 4.03 g of magnesium oxide decomposes to form 2.43 g of magnesium, what mass of oxygen gas is also released in the reaction?

1.60 g

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

A sample of sodium reacts completely with 284 g of chlorine, forming 468 g of sodium chloride. What mass of sodium reacted?

184 g

Calculate the mass of the reactants in this example: 5gNaCl+20gH2O= _______.

25 g NaCI + H2O

How many years ago was an atomic view of matter was first proposed?

2500

When added to a sealed flask and heated, 6.0 g of carbon and 16.0 g of oxygen react to form 22.0 g of carbon dioxide. How much carbon dioxide is formed when 12.0 g of carbon is reacted with 100.0 g of oxygen?

44.0 g

When 1.0 kg of mercuric oxide decomposes, 926.1 g of mercury forms. What is the mass of oxygen that forms?

73.9 g

When carbon is burned in air, it reacts with oxygen to form carbon dioxide. When 25.2 g of carbon were burned in the presence of 85.1 g of oxygen, 17.9 g of oxygen remained unreacted. What mass of carbon dioxide was produced?

92.4 g

What is the law of definite proportions?

A compound always contains the same elements in the same proportions.

Which of the following parts (postulates) of Dalton's atomic theory has been modified in light of later discoveries?

Atoms are indivisible.

Outline the main points of Dalton's atomic theory

Atoms of a given element are alike. A chemical reaction involves a rearrangement of atoms. Compounds are formed when atoms of different elements combine in fixed proportions. All matter is composed of atoms.

The scientist who in 1828 published a table of atomic weights containing 54 elements was

Berzelius

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 can be broken down into simpler substances?

CO

What was Democritus's contribution to atomic theory?

Democritus described the tiny ultimate particle as "atomos" (which means "cannot be cut").

Mendeleev was the first person to attempt to arrange the elements in a systematic order.

False

There is no difference between the hazard posed by an element when it is in a compound or by itself.

False

All of the following are molecules EXCEPT _________. NO H2 O3 H

H

The "father of modern chemistry" is

Lavoisier

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

Give two examples of how green chemistry has helped to reduce the use of lead in consumer products.

Lead free adhesives are used in electronics. Titanium dioxide replaces lead in paints.

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.

What is the Law of Conservation of Mass?

Matter is neither created nor destroyed in a chemical reaction.

Which of the following reactions is possible according to Dalton's atomic theory?

N2 + O2 -> 2NO

For which of the following would recycling of iron NOT be practical?

Rust that flakes off a car body.

When a diamond is burned, the mass that remains is zero. 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.

The carbon, which forms the diamond, has been converted to carbon dioxide and escaped into the atmosphere. The carbon in the wood is converted to carbon dioxide, but the residual ash is not. Burning the diamond in an enclosed environment would trap the carbon dioxide for further analysis.

During a chemical reaction, matter can neither be created nor destroyed.

True

Germanium was discovered in 1886. Its existence had been predicted by Mendeleev.

True

Scientists can observe computer enhanced images of atoms.

True

The Law of Constant Composition and the Law of Definite Proportions are different names for the same phenomenon.

True

Water and hydrogen peroxide are compounds composed of only hydrogen and oxygen. These compounds illustrate the Law of Multiple Proportions.

True

The Greeks thought that atoms had different shapes, with water and oil atoms being smooth and atoms associated with fire and spiciness having sharp edges. Does this view agree with Dalton's atomic theory?

Yes, it agrees with statement number two of Dalton's atomic theory: "All atoms of a given element are alike, but atoms of one element differ from atoms of any other element."

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

Dmitri Mendeleev linked the ____________ of elements to ____________ properties and created periodic law and thus the first form of the periodic table.

atomic mass; chemical

Mendeleev arranged elements in the periodic table primarily in order of their

atomic masses

Which one of the following does NOT occur in a chemical reaction?

atoms are changed into other atoms

After creating his periodic table, what was Mendeleev able to predict?

existence of elements yet undiscovered

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. Which method, if any, will immediately change the chemical form of the wastes?

incinerating wastes

Atoms of the same element that have different masses are called

isotopes

Lavoisier measured the mass of substances before and after chemical reactions and summarized his observations in a(n)

law

The fourth postulate of Dalton's Atomic Theory states that "A chemical reaction involves the rearrangement of atoms. No atoms are created, destroyed, or broken apart in a chemical reaction." Which scientific law(s) does this explain?

law of conservation of mass

What discoveries finally refuted the idea?

law of multiple proportions; law of definite proportions

Which material appears continuous to the unaided eye rather than discrete?

milk

If drops of water are subdivided to the ultimately smallest drops possible, what is the smallest particle of water that retains the chemical and physical properties of water?

molecule

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. Which method, if any, will get rid of the atoms that make up the wastes?

none of the three methods will destroy the atoms

What does the chemical formula CO2 represent?

one carbon and two oxygen atoms

Leucippus and Democritus proposed the "first" atomic view of matter. They arrived at this view based on

philosophical and intuitive speculation.

Which discovery was NOT in conflict with Dalton's atomic theory?

the discovery of the element gallium

Dalton's atomic theory states, "no atoms are created or broken apart in a chemical reaction". This is a restatement of _______________ When 3 grams of carbon is allowed to react with 8 grams of oxygen, 11 grams of carbon dioxide is formed.

the law of conservation of mass

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

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 law of multiple proportions

What law does the following list of compounds illustrate? N2O, NO, NO2, N2O4

the law of multiple proportions

How many kinds of atoms are present in a compound?

two or more

Which of the following is an example of green chemistry?

using materials that are made up of substances that are very abundant in the earth's crust