Question

melting and boiling points of some substances
substance melting point boiling point
hydrogen -259.3°c -252.9°c
nitrogen -210.0°c -195.8°c
acetic acid 16.6°c 117.9°c
gold 1064.2°c 2856°c
figure 2 - 1

1. based on the information in figure 2 - 1, the ____ point of nitrogen is -210.0°c and the ____ point of nitrogen is -195.8°c.
2. ____________ is a process that could be used to separated dissolved particles from the liquid in a solution.
3. a(an) ____________ change occurs when a material changes shape or size but composition does not change.
4. ____________ properties can be observed only when the substances in a sample of matter are changing into different substances.
5. a solid that forms and separates from a liquid mixture is a(an) ____________.
6. a cake rises as it bakes because a chemical change causes ____________ to be produced.

short answer
in complete sentences, write the answers to the questions on the lines provided.

1. how do the properties of a compound compare to the properties of the elements it contains?
2. how is the composition of a substance different from the composition of a mixture?
3. if you looked at a glass containing a solution and a glass containing a suspension, how could you tell which glass contained the suspension?

Explanation:

1. The melting point of nitrogen is -210.0°C and the boiling point is -195.8°C as per the table.
2. Evaporation or distillation can separate dissolved particles from liquid in a solution. Evaporation leaves the solid behind as the liquid turns to vapor, and distillation separates based on different boiling - points.
3. A physical change occurs when a material changes shape or size without changing composition. For example, cutting paper or melting ice.
4. Chemical properties are observed when substances change into different substances. For example, flammability or reactivity with other chemicals.
5. A solid that forms and separates from a liquid mixture is a precipitate. This often occurs in chemical reactions in solution.
6. A cake rises as it bakes because a chemical change causes gas (usually carbon - dioxide) to be produced.

1. The properties of a compound are different from the properties of the elements it contains. Compounds are formed by chemical bonds between elements, and their properties are a result of the new arrangement of atoms and the nature of the chemical bonds. For example, hydrogen and oxygen are gases, but when combined to form water, it is a liquid with different physical and chemical properties.
2. The composition of a substance is fixed and has a definite chemical formula, while a mixture has a variable composition. A substance can be an element or a compound, and its components are chemically combined. In a mixture, the components are physically mixed and can be present in different proportions.
3. A suspension contains larger particles that will settle out over time if left undisturbed. So, if one glass shows particles settling at the bottom after some time, it contains a suspension, while a solution has very small particles that do not settle and the mixture appears homogeneous.

Answer:

1. melting; boiling
2. Evaporation (or Distillation)
3. physical
4. Chemical
5. precipitate
6. gas
7. The properties of a compound are different from those of its constituent elements due to chemical bonding and new atomic arrangements.
8. A substance has a fixed composition (element or compound), while a mixture has a variable composition.
9. The glass with particles settling at the bottom contains a suspension.