b) compound – a substance of definite composition of elements
DESCRIPTION
b) Compound – a substance of definite composition of elements. It can be decomposed into two or more simpler substances by simple chemical changes but not by physical means. Example: SMORES. 1 smore contains 2 graham crackers, 1 marshmallow , and 3 chocolates. - PowerPoint PPT PresentationTRANSCRIPT
b) Compound – a substance of definite composition of elements. It can be decomposed into two or more simpler substances by simple chemical changes but not by physical means.
Example: SMORES
1 smore contains 2 graham crackers, 1 marshmallow, and 3 chocolates
6 smores contain: graham crackersmarshmallowschocolates
Ratio of crackers to marshmallows to chocolates = 2:1:3
1
126
18
1 smore contains 2 graham crackers, 1 marshmallow, and 3 chocolates
Ratio of crackers to marshmallows to chocolates = 2:1:3
2
49 graham crackers23 marshmallows69 chocolates
23 smores!
Chapter 2 Measurements and Units
1. Metric System
mass – gram, g (1 g = 0.0022 pounds)
length – meter, m (1 m = 39.37 inches)
volume – liter, L (1 L = 1.06 Quarts)
temperature – Celcius or centigrade, oC Freezing point of water = 0oC Boiling point of water = 100oC Energy – calorie, cal
1 cal = energy required to change 1 g of water 1oC Time – second, s
2. Prefix
pico p 10-12 = 0.000000000001(one-trillionth)
centimeter (cm) 1cm = 0.01 m = 1/100 m
millimeter (mm) 1 mm = 0.001 m = 1/1000 m
milliliter (mL) = 0.001 L = 1/1000 L
kilometer (km) 1 km = 1000 m
kilogram (kg) 1 kg = 1000 g
kilocalorie (kcal) 1 kcal = 1000 cal
megabite (MB) 1MB = 1,000,000 bites
gigabite (GB) 1 GB = 1,000,000,000 bites
Copyright © Houghton Mifflin Company. All rights reserved. 2–4
Figure 2.3 A cube 10 cm on a side has a volume of 1000 cm3, which is equal to 1 L.
1 c.c.
3. Accuracy and Precision Accuracy - the correctness of a measurement
Precision – reproducibility of measurements.
4. Significant figures
Copyright © Houghton Mifflin Company. All rights reserved. 2–6
Figure 2.5 The scale of a measuring device determines the magnitude of the uncertainty for the recorded measurement.
4. Significant figures
1.345 significant figures
0.2300 significant figures
0.00230
23.400500
5. Exponential notation (scientific notation)
23000000
2 significant figures
2.300 x 107
? significant figures
0.000000230 = 2.30 x 10-7
?
2.300 x 10-7 ?
= 2.3 x 107
Perfect units, exact numbers and inexact numbers
An exact number is a number whose value has no uncertaintyassociated with it – a number that arises when you count items or when you define a unit.
1 ft = 12 in1 hr = 60 min1 cm = 1/10 m½, ¼, etc.
Perfect units Exact numbers
1 kg = 2.205 lbInexact number
Infinite significant figures.
Infinite significant figures.
The value of an inexact number has a degree of uncertainty.
All measurements are inexact
Copyright © Houghton Mifflin Company. All rights reserved. 2–6
Figure 2.5 The scale of a measuring device determines the magnitude of the uncertainty for the recorded measurement.
3.8
3.75
6. Significant figure in arithmetic a) addition and subtraction
2.34 + 30.6081
+ 30.6081 2.34
32.9481 32.95
b) Multiplication and division
1.32 x 4.011 = 5.29452= 5.29
3 significant figures
6.3 x 0.000834 = 0.0053
2 significant figures
24
38
1065.310102.41021.6100.2
7. Conversion of units
It is experimentally determined that 1 inch equals 2.54 centimeters, or 1 centimeter equals 0.394 inch.
incm
cmin
154.21
54.21
Example 1Convert 2.00 inches to centimeters.
Example 2Convert 9.05 cm to inches. Factor-Label Method
Example 36.82 cm = ? feet
Example 4How many milligrams are there in 4.00 pounds?
8. Density Density = mass/volume (g/mL)
Figure 2.7 (a) The penny is less dense than the mercury it floats on. (b) Liquids that do not dissolve in one
another and that have different densities float on one another, forming layers.
a)
b)
Example 12.0 g of metal occupies 0.40 mL. What is the density?
Example 2Density = 2.0 pounds/quart = ? g/mL
Specific Gravity – ratio of the density of a substance to that of water.
Density of lead = 11.3 g/mLspecific gravity of lead = 11.3
Example:
density of water = 1.00 g /mL
no unit
9. Temperature Figure 1.4
Change of 180oF = change of 100oC
oF oC
0o
100o
32o
212o
180o 100o
Change of 180oF = change of 100oC
Change of 1oF = change of 100180
oC = change of 59
oC
Change of 1oC = = change of 95
oF
Example: 50oF = ?oC oF oC
0o32o
33o
34o1o
oF oC
0o32o
212o 100o
Absolute Temperature – Kelvin, K
K = 273 + oC
examples
FC
CF
oo
oo
3259
95)32(
10. Heat energy and specific heat
Unit of heat energy – calorie (cal)1 cal = heat needed to raise 1 g of water 1oC
1 kcal = 1000 cal1 cal = 4.184 Joules (J)
SI system
Specific heat (SH) of a substanceSH = amount of heat needed to raise 1 g of that substance 1oC
SH = heat absorbed
Mass x change of T=
calm x DT
cal = SH x m x DT
cal = SH x m x DT
SH of water = 1.0 ( cal g . oC)
Example 1 : How much heat is needed to raise 30 g water from 20oC to 30oC?
Example 2
122 cal of heat is added to 20 g of methanol at 15oC. What is the final temperature?
SH of methanol = 0.61 cal/g . oC
Example 3What quantity of heat is required to raise the temperature of 50 mL of ethanol from 22.0oC to 25.0oC? The density of ethanol at this temperature is 0.80g/mL. The specific heat of ethanol is0.59 cal/g oC.
Substance in blood Typical range
Calcium 8.5 – 10.5 mg/dLSodium 3.10 – 3.33 mg/mL Potassium 137 - 200 mg/LCholesterol 105 – 200 mg/dLFasting glucose 70 – 110 mg/dL Total protein 6.0 – 8.0 g/dL