Chapter 15 Vocabulary
Substance: a type of matter with a fixed composition.
Element: when all items in a substance have the same identity
Compound: a substance in which the atoms of two or more elements are combined in a fixed proportion.
Heterogeneous mixture: a mixture in which different materials can be distinguished easy.
Homogeneous mixture: contains 2 or more liquids, gases or solids blended together.
Solution: a homogeneous mixture of particles so small that they cannot be seen.
Colloid: a type of mixture with particles that is larger than those of solutions.
Tyndall Effect: a scattering of light do to particle movement.
Suspension: a heterogeneous mixture containing a liquid in which visible particles settle.
Physical Property: Any characteristic of a material, such as size or shape that you can observe or attempt to observe without changing the identity of the material.
Physical Change: any change in size, shape or state of matter in which the identity of the substance remains the same.
Distillation: process that can separate two substances in a mixture by evaporating a liquid and re-condensing its vapor.
Chemical Property: any characteristic of a substance such as flammability, that indicates whether it can undergo a certain chemical change.
Chemical Change: change in one substance into a new substance.
Law of Conservation of Mass: states that the mass of all substances present before a chemical change equals the mass of all
the substances remaining after the change.

Reading Check

Pg. 452
How are elements and compounds related?
  1. Elements all have atoms with the same identity. A compound is when two or more elements combine.

Pg. 454
What kind of mixture is a solution?
  1. A solution is a Homogeneous mixture of particles so small that they cannot be seen with a microscope and will never settle to the bottom of their container.

Pg. 460
Does a change in state mean that a new substance has formed? Explain.
  1. No because the substance still holds certain properties that do not change when you change its state.

Pg. 462
What is a chemical change?
  1. A chemical change is a change in one substance to another.

Pg. 465
Explain what is meant be the law of conservation of mass.
  1. A substance will have the same mass before and after a chemical change.

Caption Questions

Pg. 458
Describe the appearance of these items. (A rock and a tennis ball)
  1. A tennis ball is a small round yellow sphere that has rubber characteristics because it is bouncy. A rock is a dense material that is rough and hard.

Pg. 465
Explain why when a log is burned no mass is lost in the Chemical reaction.
  1. Because the law of conservation of mass states that the mass of all substances that are present before a chemical change equals the mass of all the substances that remain.

Applying Math

CALCULATIONS WITH THE LAW OF CONSERVATION OF MASS When a chemical reaction takes place, the total mass of reactants equals the total mass of products. If 18g of hydrogen react completely with 633g of chlorine, how many grams of HCI are formed? H2 + CI2 → 2HCI

Identify known values:
Mass of H2 = 18g
Mass of CI2 = 633g
Mass of reluctants = Mass of products

Identify unknown values:
Mass of HCI = ?g

Solve for the mass if HCI g H2 + g CI2 = g HCI
Substitute for known values. 18g +633g = 651 g HCI

CHECK: Does your answer seem reasonable? Check your answer by subtracting the mass of H2. Do you obtain the mass of the CI2? If so, the answer is correct.

  1. In the Following reaction, 24g of CH4 (methane) react completely with 96g of O2 to form 66 g of CO2. How many grams of H2O are formed? CH4 + 2O2 à CO2 + 2H2O
A. 54gH2O

  1. In the following equation, 54.0 g of AI react completely with 409.2 g of ZnCl2 to form 196.2 g of Zn metal. How many grams of AICI3 are formed? 2AI + 3ZnCI2 à 3Zn + 2AICL3
A. 463.2g = 196.2 g+ 267g AICI3

Section Assessment
Section 1

1. How is a compound similar to a homogeneous mixture? How is it different?

A homogeneous mixture contains two or more gaseous, liquid, or solid substances blended evenly. There must be more than one elements combined in a fixed proportion to create a compound. Both must have two or more parts but a homogeneous mixture deals with the physical state and a compound deals with elements and substances.

2. Distinguish between a substance and a mixture. Give two examples of each.

A substance is a type of matter with a fixed composition; a substance can be either an element or a compound. A mixture a mixture is a material made up of two or more substances that can be easily separated.
Substances: Aluminum, and Water.
Mixtures: Pizza or a Soft Drink.

3. Describe the differences between colloids and suspensions.

A colloid is a type of mixture with particles that are larger than those in solutions but not heavy enough to settle out and suspensions are a heterogeneous mixture containing a liquid in which visible particles settle.

4. Why do the words “Shake well before using” indicate that the fruit juice is a suspension?

Because shaking is needed so the visible particles that settle at the bottom are mixed into the juice.

5. In terms of suspension and colloids, compare and contrast a glass of milk and a glass of fresh-squeezed orange juice.

The milk would be filled with colloids that are not visible to the human eye when a glass of orange juice would be a suspension because the orange pulp would be easily seen be the eye.

Section 2

1. Explain why evaporation of water if a physical change and not a chemical change.

Because when water evaporates there is no chemical reactions and it is a physical change because the water does not change it just loses some water to lessen the water in the container.

2. List four physical properties you could use to describe a liquid.
1. Drains
2. Boils
3. Combines
4. Wet

3. Describe why flammability is a chemical property rather than a physical property.

Because after the substance is burned there are only ashes left but there is no mass lost in the process so that would make it chemical reaction.

4. Explain how the law of conservation of mass applies to chemical changes.

It states that the mass of all substances that are present before a chemical change equals the mass of all the substances that remain after the change, and a Chemical change is a change from one substance to another.

5. How might you demonstrate this law of conservation of mass for melting ice and distillation of water?

If you evaporate all the water and transfer it through a tube you should have the same amount of water in the end of the other tube if no water sticks to the side of the tube, and if you melt a block of ice into a bucket and then re-melt it the ice will be the same amount as before.

6. In the following equation, 417.96 g of Bi (bismuth) react completely with 200g of F (fluorine). How many grams of BiF3 (bismuth fluoride) are formed? 2Bi + 3F3 à 2BiF3
417.96g + 200g = 617.96g BiF2

Science Stats

1. Zinc acetate is approximately 35% zinc. How many grams of chewing gum would be needed to provide a total of 10.0 mg of zinc?

10.0 / .35 = 28.6

2. If you wanted to produce a gold wire as mentioned on our example, how many grams would be needed to make a wire one kilometer in length.

About 3.4 grams of gold. (100/29)

3. Table sugar has the chemical formula C12H22O11. If you were going to build a scale model of sucrose (table sugar) and you had 36 carbon model atoms, how many of each of the others (hydrogen and oxygen) would you need to build an accurate, complete sucrose model?

48 model atoms, 24 more for each.