Active Chemistry Chapter 1 Section 3

1. Avogadro's number was named after the scientist Avogadro who figured out that one mole of carbon atoms is the mass of carbon 12.

True

False

The statement is true because Avogadro's number is indeed named after the scientist Avogadro. Avogadro's number, denoted as 6.022 x 10^23, represents the number of particles (atoms, molecules, ions) in one mole of a substance. Avogadro's discovery was crucial in understanding the concept of the mole and its relationship to the mass of an element, particularly carbon-12.

Explanation

The statement is true because Avogadro's number is indeed named after the scientist Avogadro. Avogadro's number, denoted as 6.022 x 10^23, represents the number of particles (atoms, molecules, ions) in one mole of a substance. Avogadro's discovery was crucial in understanding the concept of the mole and its relationship to the mass of an element, particularly carbon-12.

2. How many atoms of oxygen are there in one unit of aluminum sulfate, Al2(SO4)3?

2

3

4

12

Anything in parentheses must be multiplied by the numbers outside and to the right of the parentheses. Since sulfate contains 4 oxygens, and there are 3 sulfate molecules, there must be this many oxygens!

Explanation

Anything in parentheses must be multiplied by the numbers outside and to the right of the parentheses. Since sulfate contains 4 oxygens, and there are 3 sulfate molecules, there must be this many oxygens!

3. The smallest representative part of an element is:

An element

A compound

An atom

A proton

The word is based off of a greek word, atomos, meaning small particle. We have now found that the atom is devised of smaller parts, but for now we will focus in the basic unit.

Explanation

The word is based off of a greek word, atomos, meaning small particle. We have now found that the atom is devised of smaller parts, but for now we will focus in the basic unit.

4. The Law of Definite Proportions states that:

Whenever two elements combine to form a compound, they do so in a definite proportion by mass.

Whenever two compounds combine to form an element, they do so in a definite proportion by volume.

Whenever two elements combine to form a compound, they do so in a definite proportion by number.

Water is 8 parts hydrogen and 1 part oxygen.

Mass is always conserved!

Explanation

Mass is always conserved!

5. John Dalton, when working with water, found that 7 parts of hydrogen reacted with 1 part of oxygen to form water. This is very close to the modern measurement, where we now know that 8 parts of hydrogen react with 1 part oxygen.

True

False

True--he was very accurate with his results using the equipment of his time...which was rare!

Explanation

True--he was very accurate with his results using the equipment of his time...which was rare!

6. What is the atomic mass of carbon?

6 g

6 amu's

12 g

12 amu's

The atomic mass of an element is the average mass of the atoms of that element, taking into account the different isotopes and their abundances. Carbon has two naturally occurring isotopes, carbon-12 and carbon-13, with atomic masses of 12 amu and 13 amu respectively. The atomic mass of carbon is calculated by taking the weighted average of these isotopes, considering their natural abundances. Therefore, the correct answer is 12 amu's.

Explanation

The atomic mass of an element is the average mass of the atoms of that element, taking into account the different isotopes and their abundances. Carbon has two naturally occurring isotopes, carbon-12 and carbon-13, with atomic masses of 12 amu and 13 amu respectively. The atomic mass of carbon is calculated by taking the weighted average of these isotopes, considering their natural abundances. Therefore, the correct answer is 12 amu's.

7. What is so special about 27 grams of Aluminum?

It is shiny

It contains 6.022 x 10^23 electrons

It is enough material to make one aluminum can

It is one mole of atoms of aluminum

While aluminum is indeed shiny, the atomic mass is the mass of 1 mole of that specific element. You can see from the periodic table that the atomic mass of Al is 27 amu's, which is one mole.

Explanation

While aluminum is indeed shiny, the atomic mass is the mass of 1 mole of that specific element. You can see from the periodic table that the atomic mass of Al is 27 amu's, which is one mole.

8. Which ending to this statement is false: Joseph Gay-Lussac was a French scientist who:

Did not agree with John Dalton's idea that all components to water formed one molecule.

Found that the volume of hydrogen was twice that of oxygen when decomposing water.

Determined the number of atoms in a mole using a relative mass.

Found that a balanced equation for the decomposition of water formed multiple water molecules.

Avogadro determined the number of atoms in a mole using a relative mass of carbon!

Review the answers to make sure you understand what Dalton did!

Explanation

Avogadro determined the number of atoms in a mole using a relative mass of carbon!

Review the answers to make sure you understand what Dalton did!