Discovering Design with Chemistry - Chapter 2 Review Questions

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Write down the original propositions for Dalton's Atomic Theory

1. All mater is made up of atoms, which are indestructible and indivisible. 2. All atoms of a given element are identical in all their properties. 3. Compounds are formed by a combination of two or more different kinds of atoms. 4. A chemical reaction is a rearrangement of the atoms that exits in the substance which are reacting.

Note anything wrong with the propositions you wrote for #10.

1. Atoms are not indestructible nor are they indivisible. 2. All atoms of a given element are not identical in all their properties.

In the situation discussed in problem #3, what is the mass of the chemical or chemicals the student didn't collect?

10.5 g

Which two of the following atoms would be isotopes? a. An atom made of 13 protons, 14 neutrons, and 13 electrons b. An atom made of 14 protons, 14 neutrons, and 14 electrons c. An atom made of 13 protons, 12 neutrons, and 13 electrons d. An atom made of 15 protons, 16 neutrons, and 15 electrons

A and C would be isotopes.

Water is a compound that can be broken down into hydrogen gas and oxygen gas. However, a mixture of hydrogen gas and oxygen gas looks and behaves nothing like water. Why?

A mixture of hydrogen gas and oxygen gas looks and behaves nothing like water because, in a mixture the elements involved retain their individual properties, while in a compound the elements lose their individual properties when they combined to make a pure substance that has totally new properties

A chemist is making two different compounds from the same two elements: nitrogen and oxygen. To make the first gas, she reacts 10.0 grams of nitrogen and 11.42 grams of oxygen to make 21.42 grams of the first gas. Suppose she starts with 10.0 grams of nitrogen again but wants to make a completely different gas with no leftover oxygen. Should she use 20.50 grams of oxygen, 22.84 grams of oxygen, or 35.12 grams of oxygen?

Help?

In an experiment, a chemist reacts 7.85 grams of manganese with 2.29 grams of oxygen to make 10.14 grams of a powder. Is it the same as the powder made in problem #7?

No, this is a different powder then that which was made in problem #7

Which of the two isotopes you found in #19 would be the heaviest?

Option A would be the heaviest.

When you burn a fuel, what besides the fuel gets used up?

Oxygen

What particles do you find in the nucleus of an atom?

Protons and Neutrons

Give the sign of the electrical charge on each of the particles listed in #14

Protons: + Neutrons: no charge Electrons: -

Of the three particles that make up most atoms, there is one particle that doesn't appear in some hydrogen atoms. Which is it?

The Neutron

Describe the planetary model of the atom and indicate who proposed it.

The planetary model was proposed by the English physicist Ernest Rutherford. It is called the planetary model because, it has the same structure as our solar system. Just as the planets orbit the sun in the solar system, the electrons orbit the protons in Rutherford model.

Describe the plum pudding model of the atom and indicate what experiment demonstrated it wasn't correct.

The plum pudding model was developed by scientists while they were still unaware of the existence of neutrons. It was called the plum pudding model because, it had the positive charges distributed throughout the atom, like the pudding. The electrons were small particles embedded in the pudding, like "plums". However, an experiment preformed in the later parts of the 19th century by English physicist Ernest Rutherford, showed that the model could not be correct.

A chemist makes two different compounds from the same two elements: tin and chlorine. He reacts 50.0 grams of tin with 29.87 grams of chlorine. There are no leftovers from either element. He then reacts 50.0 grams of tin with 59.74 grams of chlorine. Once again, there are no leftovers. If the first compound has two atoms of chlorine in the molecule, how many atoms of chlorine are in a molecule of the second compound?

The second compound will have 4 chlorine atoms

A chemist makes 86.94 grams of a black powder by reacting 54.94 grams of manganese with 32.00 grams of oxygen. If a student breaks down 144.9 grams of that powder, what mass of manganese and what mass of oxygen will be made?

The student would make 91.58 grams of manganese and 53.34 grams of oxygen.

What three particles make up most atoms?

The three particles that make up most atoms are: Protons, Neutrons and Electrons

In another experiment, a chemist reacts 10.0 grams of manganese with 5.8 grams of oxygen to make 15.8 grams of a powder. Is this the same as the powder made in problem #7?

Yes, this is the same powder made in problem #7

A 75.0-gram sample of a white powder is chemically broken down into 29.86 grams of copper, 15.06 grams of sulfur, and an unknown amount of oxygen gas. a. How much oxygen gas was made? b. Suppose you want to make 11.2 grams of the white powder with no leftovers. How much copper, sulfur, and oxygen would you have to use?

a. 30.1 Grams of oxygen were made. b. One would need 4.45g of copper, 2.24g of sulfur and 4.48g of oxygen.

Classify the following as an element, compound, heterogeneous mixture, or homogeneous mixture. a. A bowl of fruit covered with yogurt b. A sample of helium gas, which cannot be broken down into simpler substances c. A sample of sugar thoroughly dissolved in water d. A sample of sodium bicarbonate (baking soda), which can be broken down into hydrogen, carbon, oxygen, and sodium. e. Several grams of magnesium, which is one of the two simplest substances produced when magnesium oxide breaks down. f. The magnesium oxide from which the magnesium discussed above was produced. g. A strawberry h. A cup of tea with no leaves in it.

a. Heterogeneous Mixture b. Element c. Homogeneous Mixture d. Compound e. Element f. Compound g. Heterogeneous mixture h. Homogeneous Mixture

A student does a chemical reaction with two chemicals. The total mass of the two chemicals is 45.0 grams. When she is done, she finds that the mass of all the chemicals she has collected is now only 34.5 grams. Has she collected all the products of the reaction? (a) How do you know? (b)

a. No, she has not collected all the products of the reaction. b. I know that she has not collected all the products of the reaction because, the Law of Mass Conservation states that, "In any chemical or physical process, the total mass of everything involved must remain the same", and since she started with 45.0 g and ended with 34.5 g, she must not have collected all the products of the reaction.

Define the following terms: a. Pure substance b. Mixture c. Homogeneous Mixture d. Heterogeneous Mixture e. Law of Mass Conservation f. Element: g. Compound h. Law of Definite Proportions i. Molecule j. Law of Multiple Proportions k. Isotopes

a. Pure substance - A substance whose properties are the same throughout. b. Mixture - A combination of two or more pure substances. c. Homogeneous Mixture - A mixture whose composition is the same throughout the sample. d. Heterogeneous Mixture - A mixture whose composition is different in different parts of the sample. e. Law of Mass Conservation - In any chemical or physical process, the total mass of everything involved must remain the same. f. Element - A substance that cannot be chemically broken down into simpler substances. g. Compound - A pure substance that is composed of two or more elements. h. Law of Definite Proportions - A given compound will always have the same proportion of elements by mass. i. Molecule - A combination of two or more atoms joined together. j. Law of Multiple Proportion - When two elements combine to form different compounds, a fixed amount of one element will combined with the other element so that the ratio of the masses of the other element is a small whole number. k. Isotopes - Two or more atoms of the same element that have different numbers of neutrons.


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