Download presentation

1
**I. Units of Measurement (p. 33 - 39)**

CH. 2 - MEASUREMENT I. Units of Measurement (p )

2
A. Number vs. Quantity Quantity - number + unit UNITS MATTER!!

3
**B. SI Units Quantity Symbol Base Unit Abbrev. Length l meter m Mass m**

kilogram kg Time t second s Temp T kelvin K Amount n mole mol

4
**B. SI Units Prefix Symbol Factor mega- M 106 kilo- k 103 BASE UNIT ---**

100 deci- d 10-1 centi- c 10-2 milli- m 10-3 micro- 10-6 nano- n 10-9 pico- p 10-12

5
**M V D = C. Derived Units 1 cm3 = 1 mL 1 dm3 = 1 L**

Combination of base units. Volume (m3 or cm3) length length length 1 cm3 = 1 mL 1 dm3 = 1 L D = M V Density (kg/m3 or g/cm3) mass per volume

6
D. Density Mass (g) Volume (cm3)

7
**Problem-Solving Steps**

1. Analyze 2. Plan 3. Compute 4. Evaluate

8
**D. Density V = 825 cm3 M = DV D = 13.6 g/cm3 M = (13.6 g/cm3)(825cm3)**

An object has a volume of 825 cm3 and a density of 13.6 g/cm3. Find its mass. GIVEN: V = 825 cm3 D = 13.6 g/cm3 M = ? WORK: M = DV M = (13.6 g/cm3)(825cm3) M = 11,200 g

9
**D. Density D = 0.87 g/mL V = M V = ? M = 25 g V = 25 g 0.87 g/mL**

A liquid has a density of 0.87 g/mL. What volume is occupied by 25 g of the liquid? GIVEN: D = 0.87 g/mL V = ? M = 25 g WORK: V = M D V = g 0.87 g/mL V = 29 mL

10
**II. Using Measurements (p. 44 - 57)**

CH. 2 - MEASUREMENT II. Using Measurements (p )

11
**A. Accuracy vs. Precision**

Accuracy - how close a measurement is to the accepted value Precision - how close a series of measurements are to each other ACCURATE = CORRECT PRECISE = CONSISTENT

12
**B. Percent Error Indicates accuracy of a measurement your value**

accepted value

13
**B. Percent Error % error = 2.9 %**

A student determines the density of a substance to be 1.40 g/mL. Find the % error if the accepted value of the density is 1.36 g/mL. % error = 2.9 %

14
**C. Significant Figures Indicate precision of a measurement.**

Recording Sig Figs Sig figs in a measurement include the known digits plus a final estimated digit 2.35 cm

15
**C. Significant Figures Counting Sig Figs (Table 2-5, p.47)**

Count all numbers EXCEPT: Leading zeros Trailing zeros without a decimal point -- 2,500

16
**Counting Sig Fig Examples**

C. Significant Figures Counting Sig Fig Examples 4 sig figs 3 sig figs 3. 5,280 3. 5,280 3 sig figs 2 sig figs

17
**C. Significant Figures (13.91g/cm3)(23.3cm3) = 324.103g 324 g**

Calculating with Sig Figs Multiply/Divide - The # with the fewest sig figs determines the # of sig figs in the answer. (13.91g/cm3)(23.3cm3) = g 4 SF 3 SF 3 SF 324 g

18
**C. Significant Figures 3.75 mL + 4.1 mL 7.85 mL 3.75 mL + 4.1 mL**

Calculating with Sig Figs (con’t) Add/Subtract - The # with the lowest decimal value determines the place of the last sig fig in the answer. 3.75 mL mL 7.85 mL 3.75 mL mL 7.85 mL 224 g + 130 g 354 g 224 g + 130 g 354 g 7.9 mL 350 g

19
**C. Significant Figures Calculating with Sig Figs (con’t)**

Exact Numbers do not limit the # of sig figs in the answer. Counting numbers: 12 students Exact conversions: 1 m = 100 cm “1” in any conversion: 1 in = 2.54 cm

20
**C. Significant Figures Practice Problems 5. (15.30 g) ÷ (6.4 mL)**

4 SF 2 SF = g/mL 2.4 g/mL 2 SF g g 18.1 g 18.06 g

21
**D. Scientific Notation 65,000 kg 6.5 × 104 kg**

Converting into Sci. Notation: Move decimal until there’s 1 digit to its left. Places moved = exponent. Large # (>1) positive exponent Small # (<1) negative exponent Only include sig figs.

22
**D. Scientific Notation Practice Problems 7. 2,400,000 g 8. 0.00256 kg**

9. 7 10-5 km 104 mm 2.4 106 g 2.56 10-3 kg km 62,000 mm

23
**D. Scientific Notation Calculating with Sci. Notation**

(5.44 × 107 g) ÷ (8.1 × 104 mol) = Type on your calculator: EXP EE EXP EE ENTER EXE 5.44 7 8.1 ÷ 4 = = 670 g/mol = 6.7 × 102 g/mol

24
**Chemistry Binder Organization**

25
**III. Unit Conversions (p. 40 - 42)**

CH. 2 - MEASUREMENT III. Unit Conversions (p )

26
**A. SI Prefix Conversions**

Symbol Factor mega- M 106 kilo- k 103 BASE UNIT --- 100 deci- d 10-1 move left move right centi- c 10-2 milli- m 10-3 micro- 10-6 nano- n 10-9 pico- p 10-12

27
**M V D = C. Derived Units 1 cm3 = 1 mL 1 dm3 = 1 L**

Combination of base units. Volume (m3 or cm3) length length length 1 cm3 = 1 mL 1 dm3 = 1 L D = M V Density (kg/m3 or g/cm3) mass per volume

28
D. Density Mass (g) Volume (cm3)

29
**Problem-Solving Steps**

1. Analyze 2. Plan 3. Compute 4. Evaluate

30
**D. Density V = 825 cm3 M = DV D = 13.6 g/cm3 M = (13.6 g/cm3)(825cm3)**

An object has a volume of 825 cm3 and a density of 13.6 g/cm3. Find its mass. GIVEN: V = 825 cm3 D = 13.6 g/cm3 M = ? WORK: M = DV M = (13.6 g/cm3)(825cm3) M = 11,200 g

31
**D. Density D = 0.87 g/mL V = M V = ? M = 25 g V = 25 g 0.87 g/mL**

A liquid has a density of 0.87 g/mL. What volume is occupied by 25 g of the liquid? GIVEN: D = 0.87 g/mL V = ? M = 25 g WORK: V = M D V = g 0.87 g/mL V = 29 mL

32
Homework P. 54 Practice problems 1 & 2

33
**Conversion Factors Problems**

Dimensional Analysis Conversion Factors Problems

34
**B. Dimensional Analysis**

A tool often used in science for converting units within a measurement system Conversion Factor A numerical factor by which a quantity expressed in one system of units may be converted to another system

35
**B. Dimensional Analysis**

The “Factor-Label” Method Units, or “labels” are canceled, or “factored” out

36
**B. Dimensional Analysis**

Steps: 1. Identify starting & ending units. 2. Line up conversion factors so units cancel. 3. Multiply all top numbers & divide by each bottom number. 4. Check units & answer.

37
**B. Dimensional Analysis**

Lining up conversion factors: = 1 1 in = 2.54 cm 2.54 cm cm 1 = 1 in = 2.54 cm 1 in in

38
**B. Dimensional Analysis**

How many milliliters are in 1.00 quart of milk? qt mL 1.00 qt 1 L 1.057 qt 1000 mL 1 L = 946 mL

39
**B. Dimensional Analysis**

You have 1.5 pounds of gold. Find its volume in cm3 if the density of gold is 19.3 g/cm3. lb cm3 1.5 lb 1 kg 2.2 lb 1000 g 1 kg 1 cm3 19.3 g = 35 cm3

40
**B. Dimensional Analysis**

How many liters of water would fill a container that measures 75.0 in3? in3 L 75.0 in3 (2.54 cm)3 (1 in)3 1 L 1000 cm3 = 1.23 L

41
**B. Dimensional Analysis**

5) Your European hairdresser wants to cut your hair 8.0 cm shorter. How many inches will he be cutting off? cm in 8.0 cm 1 in 2.54 cm = 3.2 in

42
**B. Dimensional Analysis**

6) Taft football needs 550 cm for a 1st down. How many yards is this? cm yd 550 cm 1 in 2.54 cm 1 ft 12 in 1 yd 3 ft = 6.0 yd

43
**B. Dimensional Analysis**

7) A piece of wire is 1.3 m long. How many 1.5-cm pieces can be cut from this wire? cm pieces 1.3 m 100 cm 1 m 1 piece 1.5 cm = 86 pieces

Similar presentations

© 2019 SlidePlayer.com Inc.

All rights reserved.

To make this website work, we log user data and share it with processors. To use this website, you must agree to our Privacy Policy, including cookie policy.

Ads by Google