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Measurements & Units

Measurements & Units. Chapter 1. Characterization. In order to characterize matter , we need to record its properties . Many Intensive properties are qualitative . Qualitative properties are characteristics that cannot be measured .

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Measurements & Units

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  1. Measurements & Units Chapter 1

  2. Characterization In order to characterize matter, we need to record its properties. Many Intensive properties are qualitative. Qualitative properties are characteristics that cannot be measured. When qualitative properties are noted, the quality of the substance is described. Some examples are color, luster, reactivity, & conductivity.

  3. Characterization w/ Numbers Extensive & some Intensive properties are quantitative. Quantitative properties are characteristics that have to be measured. When quantitative properties are noted, the quantity of the substance is described. All quantitative properties must have a number and a unit. Numbers without units are meaningless. ALWAYS REMEMBER THE UNITS!!!

  4. Quantitative Properties Some examples are: Mass Length Temperature Volume Boiling & Melting points, & Density.

  5. Quantitatively Speaking Some quantitative properties are measured directly using some tool. They are called direct measurements and carry the units of the tool. For example, measuring the length of a piece of steel with a meter stick will give you a quantitative property, length, with centimeters as the unit.

  6. Indirection Some characteristics cannot be measured directly. They must be calculated from other direct measurements. Properties like this are called derived measurements. Derived measurements include the units of each other measurement used to derive them.

  7. Derived Properties For example, the volume of a cube must be calculated. If a side of a cube measures 4 cm, then the volume is 4 cm x 4 cm x 4 cm = 64 cm3

  8. Another One Speed is another derived quantitative property. It is calculated using distance traveled per unit of time. For example, if a ball rolls 24 meters in 5 seconds, its speed is 24 m / 5 s = 4.8 m/s

  9. Intensive from Extensive Some Intensive properties can be derived from Extensive properties. Density is a quantitative Intensive property that is derived from two quantitative Extensive properties: mass and volume. But more on that later…

  10. What is Chemistry? • The study of Matter. • Specifically, it is the study of • Chemicals, • Their properties and behaviors, • And the changes they undergo.

  11. What is a Chemical? • A substance that has a definite Composition (it’s always the same). • For example, Water is H2O • It’s the same here in Moorestown as it is in California – still the same stuff on Mars

  12. Scientific Method Observations Revise (if necessary) Hypothesis Experiment Results Conclusions

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