# Appendix 1 - Measurements - PowerPoint PPT Presentation

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Appendix 1 - Measurements. We make QUALITATIVE observations of reactions — changes in color and physical state. We also make QUANTITATIVE MEASUREMENTS , which involve numbers . Use SI units —(International System of Units) based on the metric system. Standards of Measurement.

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Appendix 1 - Measurements

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### Appendix 1 - Measurements

• We makeQUALITATIVEobservations of reactions — changes in color and physical state.

• We also makeQUANTITATIVE MEASUREMENTS, which involve numbers.

• UseSI units—(International System of Units) based on the metric system

### Standards of Measurement

When we measure, we use a measuring tool to compare some dimension of an object to a standard.

For example, at one time the standard for length was the king’s foot. What are some problems with this standard?

### Some Tools for Measurement

Which tool(s) would you use to measure:

A. temperature

B. volume

C. time

D. weight

### Learning Check

Match L) length M) mass V) volume

____ A. A bag of tomatoes is 4.6 kg.

____ B. A person is 2.0 m tall.

____ C. A medication contains 0.50 g Aspirin.

____ D. A bottle contains 1.5 L of water.

M

L

M

V

### S.I. Measurement

Based on:

- number

- units

- accuracy report

S.I. Units are:

- related by factors of 10

* Table C of Reference Tables

### Metric Prefixes

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• Kilo- 10 or 1 kilometer = 10 m

1 km or 1000 m

10 m 1 km

• Centi- 10 or 100 centimeters = 1 meter

100 cm or 1 m

1 m 100 cm

• Milli- 10 or 1000 mm

1 m

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### Base Units

• Length = meter (m)

• Mass = kilogram (kg) also gram (g)

Mass vs. Weight

Mass: Amount of Matter

Weight: Force exerted by the mass, only present with gravity

### Temperature

• Kelvin (K)

• Measure of the average kinetic energy

*Thermometer is a molecular speedometer. Shows vibrational energy.

• Table T of

Reference Tables

### Time

The base unit for time = seconds (s)

60 seconds = 1 minute = 1/60 hour

### Amount of a Substance

• Measured in moles (mol)

• Contains Avogadro’s number of particles

• 6.02 X 10

• 602,000,000,000,000,000,000,000

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### Derived Units - Volume

• Liter (L)

• Volume = L X W X H

• 1cm X 1cm X 1cm = cm or 1ml

• 1dm X 1dm X 1dm = dm or 1L

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### Derived Units – Heat Energy

• Joules (J)

• 4.18 J = the energy needed to raise the temperature of 1 gram of water 1 degree K.

• Table B of Reference Tables – Specific Heat of Water

Heat (q) = 4.18J/gK X g (water) X t

### Heat Energy

• Suppose that a calorimeter contains 200. grams of water at 294.0 K. As an exothermic reaction occurs the water temperature rises to 314.0 K.

• What is the quantity of heat transferred?

• Temperature change of 20.0 K for 200g water.

• q= 4.18 J/gK X 200g X 20.0 K

• q= 16,720 J or 16.7 KJ

1 calorie = 4.18 Joules

### Pressure

• Pascal (Pa)

• Pa = force

unit area

• Table A of Reference Tables

• 1 atm = 101.3 kPa

### Density

• Table T of Reference Tables

• Solve for m

D X V = m

• Solve for V = m

D

### Density Practice

• What is the density of an object with a mass of 20.1g and a volume of 142.5cm ?

• What is the mass of an object with a density of 32.1 g/cm and a volume of 10.0cm ?

• What is the volume of an object with a mass of 40g and a density of 10g/cm ?

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