Goal 4 Chemsitry Review #2

1. Marquis is studying an unknown substance. He has recorded several properties in his notebook. Which of these properties is a physical property?

Boiling point

Flammability

Tendency to tarnish

Tendency to rust

All other properties are chemical because they result from a chemical reaction.

Explanation

All other properties are chemical because they result from a chemical reaction.

2. There are three mixtures listed below. Which one, if any, could not be seperated by evaporation?

Salt and water

Sawdust and water

Iron fillings and water

All of these mixtures could be separated by evaporation

All of these mixtures could be separated by evaporation because evaporation is a physical process that involves the conversion of a liquid into a gas, leaving behind the solid components. In the case of salt and water, the water can be evaporated, leaving the salt behind. Similarly, in the case of sawdust and water, the water can be evaporated, leaving the sawdust behind. Lastly, in the case of iron filings and water, the water can be evaporated, leaving the iron filings behind.

Explanation

All of these mixtures could be separated by evaporation because evaporation is a physical process that involves the conversion of a liquid into a gas, leaving behind the solid components. In the case of salt and water, the water can be evaporated, leaving the salt behind. Similarly, in the case of sawdust and water, the water can be evaporated, leaving the sawdust behind. Lastly, in the case of iron filings and water, the water can be evaporated, leaving the iron filings behind.

3. Which phase has the greatest density?

Solid

Liquid

Gas

The temp must be known to answer this question

Since the particles in a solid are tightly packed, it makes solids have a higher density.

Explanation

Since the particles in a solid are tightly packed, it makes solids have a higher density.

4. Which of the following is the heaviest?

The electron

The proton

The nuetron

The nucleus

The nucleus contains the protons plus the neutrons making it heavier, than just one or the other.

Explanation

The nucleus contains the protons plus the neutrons making it heavier, than just one or the other.

5. How does perspiration cool your skin?

It carries heat off when it condenses on your skin

It carries heat off when it evaporates from your skin

It carries heat off when it sublimes from your skin

It carries heat off when it deposits on your skin

It takes heat to cause the water to evaporate. So each droplet that evaporates has trapped some heat in it.

Explanation

It takes heat to cause the water to evaporate. So each droplet that evaporates has trapped some heat in it.

6. The components of a homogeneous mixture could be described as

Inseperable

Evenly mixed

Chemically bound

Unevenly mixed

Mixtures are physically put together not physically. Homogeneous means same thoughout and heterogeneous means unevenly distributed.

Explanation

Mixtures are physically put together not physically. Homogeneous means same thoughout and heterogeneous means unevenly distributed.

7. Neutral lithium has 3 protons. During a chemical reaction, 1 electron is removed. How many protons does lithium have now?

3

2

1

You must know what element lithium reacted with to determine this.

The number of protons does not change in a chemical reaction, only the number of electrons. The new electron number is the problem would be 2.

Explanation

The number of protons does not change in a chemical reaction, only the number of electrons. The new electron number is the problem would be 2.

8. The nucleus of an atom has an overall ____________ charge.

Positive

Negative

Neutral

Empty

Since protons are positive, and they reside in the nucleus, the nucleus is positive.

Explanation

Since protons are positive, and they reside in the nucleus, the nucleus is positive.

9. Electron clouds (orbitals) contain

Thousands of fast-moving electrons

A few fast-moving protons

A few-fast moving electrons

Many nuclei

No atom has more than 125 electrons total.

Explanation

No atom has more than 125 electrons total.

10. The chemical combination of Atom A and Atom B would result in

An atom AB

An element AB

A molecule AB

A nucleus AB

Molecule implies a compound. When two or elements combine, you get a compound. An atom is just one element. An element is an atom of the same kind.

Explanation

Molecule implies a compound. When two or elements combine, you get a compound. An atom is just one element. An element is an atom of the same kind.

11. Which of the following is a positive ion?

Barium (Ba) with 56 electrons and 58 protons

Sodium (Na) wil 11 protons and 11 electrons

Oxygen (O) with 8 protons and 10 electrons

Chlorine (Cl) with 17 protons and 18 electrons

Protons are positive and electrons are negative, so since Barium has more protons it will have a +2 charge.

Explanation

Protons are positive and electrons are negative, so since Barium has more protons it will have a +2 charge.

12. Tina uses a vice to squeeze each container. Which turns out to be the most compressible?

The solid phase container

The liquid phase container

The gas phase container

The temp must be known to answer this question

Since the particles in a gas are far apart, there is alot of empty space in a gas. This allows the gas to be compressed.

Explanation

Since the particles in a gas are far apart, there is alot of empty space in a gas. This allows the gas to be compressed.