Chapter 2 Answers
1. Extensive and Intensive
2. Intensive properties like density depend on the type of matter in a sample, not the amount of matter. If the substance is the same then the intensive properties are the same.
3. Solid, Liquid, Gas…(the fourth state is called plasma)
4. Reversible, like melting and freezing of water, and irreversible, like tearing a piece of paper in half.
5. Color…all the other substances in the table have different colors.
6. Liquid and gases have indefinite shapes and take the shape of the container, while solids have definite shape. In addition, particles in a liquid, although in close contact, are free to flow past one another. In a solid, they are in close contact, typically arranged in an ordered fashion, but stuck vibrating in place.
7. It is reversible since solid mercury can melt back to a liquid by increasing the temperature.
8. Extensive properties depend on the amount of matter in a sample…like mass and volume. Two difference substances can have the same mass or have the same volume. For example, a liter of water and a liter of mercury, or 100 grams of sucrose or 100g of copper. Intensive properties do not depend on amount of matter, but type of matter. For example, the density of gold and the density of copper will always be different.
9. Iron filings are attracted to a magnet, while sodium chloride is not…iron is ferromagnetic.
10. The air needs to first be cooled down so that is condenses into a liquid (about -200 degrees C). One can then use distillation since nitrogen and oxygen have different boiling points. Nitrogen will boil at -195C and oxygen will boil at -183C.
11. Homogeneous (solution) or Heterogeneous
12. Physical properties like size (filtration), boiling point (distillation), magnetism, density (centrifugation), Solubility (crystallization)
13. A phase is any part of a sample that is homogeneous. A homogeneous sample will have one phase, while a heterogeneous sample will have more than one phase.
14.
- homogeneous
- heterogeneous
- homogeneous
- heterogeneous
15. A substance is a pure element or compound, not a solution/homogeneous mixture. A solution is a homogeneous mixture meaning a uniform mixture of more than one substance.
16. Filtration is used when you have a solid mixed with a liquid. Distillation is used when two liquids with difference boiling points are mixed.
17. To separate the sand one would use filtration leaving behind salt water. One can then evaporate the water leaving behind the salt. If you want to collect/save the water then a distillation apparatus is needed.
18. Container B contained a mixture of a solid dissolved in a liquid solvent (ex. water). When the solvent evaporated, the solid was left behind. Container A may have contained only the solvent (ex. water). Container A could have also had a mixture of liquid that were all able to evaporate.
19. The clear liquid had to be a mixture since a solid was left behind after evaporation indicating that the solid was dissolved in the liquid (more than one substance present).
20. A compound is contains two or more elements chemically combined (ionically bonded or covalently bonded). An element is composed solely of one element (one type of atom) like O2 or C60.
21. Mixtures can have variable compositions. For example, salt water can be 10% NaCl or 30% NaCl. The amount of water and salt can vary. However, pure water cannot vary…it is always 100% water.
22. Symbols like Au or Pt represent elements, while chemical formulas like NaCl or H2O represent compounds.
23. Compounds can be broken down using heat and electricity. Chemical reactions can also be used to break down compounds like reacting sucrose with sulfuric acid, which will break the sucrose down into water and carbon. The water can then be broken down into hydrogen and oxygen using electricity (electrolysis).
24.
- Compound (sucrose)
- Mixure
- Mixture
- Element
25.
- Pb
- O
- Ag
- Na
- H
- Al
26.
- Carbon
- Calcium
- Potassium
- Gold
- Iron
- Copper
27. Carbon, Hydrogen, Oxygen, and Nitrogen. Hydrogen is in the greatest proportion by particle number.
28. The composition always changes. By definition, a chemical reaction (chemical change) is when one or more substances change into one or more new substances.
29. Four clues include a transfer of energy (heat absorbed or released), a color change, production of a gas, or the formation of a precipitate (a solid).
30. Law of conservation of mass – the mass of the reactants, which become the products, must equal the mass of the products. You cannot just lose mass…
31. A physical change does NOT involve a chemical reaction like melting or freezing – the substance does not change. A chemical change does involved a chemical reaction and substances are converted to new substances.
32.
- Physical (it is still water)
- Chemical change – this one is tough…you are breaking an ionic bond between the Na+ and Cl- when you dissolve it in water. However, if you dissolve glucose, this is a physical change because glucose is a molecule and nothing is being separated.
- Chemical
- Chemical
33. It is conserved in ANY physical or chemical change (reaction).
34. Since mass must be conserved, you just add them up…43.2 grams.
37. reddish color, conductor of heat and electricity, malleable, melting and boiling points
41. Gaseous acetone is a vapor. Vapors are normally liquid or solid at room temp.
44. Sharpening a pencil is irreversible, freezing water is reversible
45. Mass is extensive and does not depend on composition.
46. Malleability is an intensive property because it depends on the type of matter, not the amount.
47. ethanol
48. neon
53. Particles in a gas are free to move, so a container is needed. Particles in a solid do not move relative to each other, so solids have a definite shape and volume without a container.
54. Change in appearance can occur when no change in composition takes place, such as in a change of state or shape.
55. a. mercury and sulfur
b. For both elements, 125C is between the melting and boiling point.
c. ethanol, mercury, bromine, and water would be in a different order, and gold and copper would be switched.
56. Heterogeneous mixtures have a non-uniform composition. Homogeneous mixtures have uniform composition.
58. a. heterogeneous b. homogeneous c. heterogeneous. d. homogeneous
59. filter out the sand and charcoal. Burn the sand and charcoal in an oven. The charcoal will burn off as CO2 and H2O leaving behind the sand.
60. A compound can be separated into its elements by chemical means. Elements cannot be broken down by chemical means any further.
63. Mixtures…almost all matter is a mixture of many substances. A pure substance is hard to come by in nature.
64. Yes, because the graph is a straight line. The proportion of iron to oxygen is constant, as it would be in a compound. B. No, this point does not lie on the straight line indicating that the ratio of iron to oxygen is different than it is in the other samples.
65. With heat, iron and sulfur change into a new substance, iron sulfide. In a chemical change, such as this, composition changes. In a physical change, chemical composition remains the same.
66. chemical property
67. 18g of water
68. a. Both are elements, pure substances, and solids at room temp. They differ in color, melting point and boiling point. B. Both are clear liquids at room temp. Distilled water is a compound, and saltwater is a mixture.
RPE
1. 1
2. 1
3. 2
4. 4
5. 2
6. 4
7. 1
8. 3
9. 2
10. 1
11. 3
12. 4
13. 3
14. 3
15. a. 4.3g b. 22.6g c. 19.0g
16. graph it
17. 13.3 g of magnesium oxide
18. 12.1 g magnesium and 7.9 g oxygen
19. gallium will freeze first and mercury last
20. the mass of the rust is the sum of the mass of the iron and the mass of the oxygen that combined with it
21. a. heterogeneous mixture b. homogeneous mixture c. heterogeneous mixture and compound d. heterogeneous mixture
22. a-d physical e. chemical
23. a. nitrogen, hydrogen
b. potassium, oxygen
c. carbon, hydrogen, oxygen
d. calcium, sulfur
24. a. physical
b. chemical – energy released, color change
c. chemical – production of a gas, odor change
d. physical