Chapter 1 Introduction(1.00)(0.100)(40.00g NaOH) # g NaOH = -----(1) (1) = 4.00 g NaOH Weigh 4.00 g...

25
1 Chapter 1 Introduction Analytical Chemistry qualitative analysis (Chem 101-103) quantitative analysis

Transcript of Chapter 1 Introduction(1.00)(0.100)(40.00g NaOH) # g NaOH = -----(1) (1) = 4.00 g NaOH Weigh 4.00 g...

Page 1: Chapter 1 Introduction(1.00)(0.100)(40.00g NaOH) # g NaOH = -----(1) (1) = 4.00 g NaOH Weigh 4.00 g of NaOH, transfer to a 1.00 L volumetric flask, and dilute to the line. Dilution

1

Chapter 1

Introduction

Analytical Chemistry

• qualitative analysis (Chem 101-103)

• quantitative analysis

Page 2: Chapter 1 Introduction(1.00)(0.100)(40.00g NaOH) # g NaOH = -----(1) (1) = 4.00 g NaOH Weigh 4.00 g of NaOH, transfer to a 1.00 L volumetric flask, and dilute to the line. Dilution

2

Quantitative Analysis

• gravimetric

• volumetric

• electroanalytical

• spectroscopic

• chromatographic (if time allows)

Analytical Terminology

• heterogeneous

• homogeneous

• analyte

Page 3: Chapter 1 Introduction(1.00)(0.100)(40.00g NaOH) # g NaOH = -----(1) (1) = 4.00 g NaOH Weigh 4.00 g of NaOH, transfer to a 1.00 L volumetric flask, and dilute to the line. Dilution

3

Steps in a Chemical Analysis

• Sampling: representative

• Sample Preparation

• Analyzing the Sample

• Interpreting the results

Page 4: Chapter 1 Introduction(1.00)(0.100)(40.00g NaOH) # g NaOH = -----(1) (1) = 4.00 g NaOH Weigh 4.00 g of NaOH, transfer to a 1.00 L volumetric flask, and dilute to the line. Dilution

4

Grind to small pieces

Extraction

Decant, quantitative transfer, supernatant liquid

Page 5: Chapter 1 Introduction(1.00)(0.100)(40.00g NaOH) # g NaOH = -----(1) (1) = 4.00 g NaOH Weigh 4.00 g of NaOH, transfer to a 1.00 L volumetric flask, and dilute to the line. Dilution

5

Page 6: Chapter 1 Introduction(1.00)(0.100)(40.00g NaOH) # g NaOH = -----(1) (1) = 4.00 g NaOH Weigh 4.00 g of NaOH, transfer to a 1.00 L volumetric flask, and dilute to the line. Dilution

6

Page 7: Chapter 1 Introduction(1.00)(0.100)(40.00g NaOH) # g NaOH = -----(1) (1) = 4.00 g NaOH Weigh 4.00 g of NaOH, transfer to a 1.00 L volumetric flask, and dilute to the line. Dilution

7

Page 8: Chapter 1 Introduction(1.00)(0.100)(40.00g NaOH) # g NaOH = -----(1) (1) = 4.00 g NaOH Weigh 4.00 g of NaOH, transfer to a 1.00 L volumetric flask, and dilute to the line. Dilution

8

Page 9: Chapter 1 Introduction(1.00)(0.100)(40.00g NaOH) # g NaOH = -----(1) (1) = 4.00 g NaOH Weigh 4.00 g of NaOH, transfer to a 1.00 L volumetric flask, and dilute to the line. Dilution

9

Analyzing the Sample

Step 1. Obtain a representative bulk sample.

Step 2. Extract from the bulk sample asmaller, homogeneous laboratory sample.

Step 3. Convert the laboratory sample into aform suitable for analysis, a process thatusually involves dissolving the sample.

Page 10: Chapter 1 Introduction(1.00)(0.100)(40.00g NaOH) # g NaOH = -----(1) (1) = 4.00 g NaOH Weigh 4.00 g of NaOH, transfer to a 1.00 L volumetric flask, and dilute to the line. Dilution

10

Analyzing the Sample

Step 4. Remove or mask species that willinterfere with the chemical analysis.

Step 5. Measure the concentration of theanalyte in several aliquots.

Step 6. Interpret your results and drawconclusions.

SI Prefixes

especially useful in this course

mega M 106

kilo k 103

centi c 10-2

milli m 10-3

micro 10-6

nano n 10-9

pico p 10-12

Page 11: Chapter 1 Introduction(1.00)(0.100)(40.00g NaOH) # g NaOH = -----(1) (1) = 4.00 g NaOH Weigh 4.00 g of NaOH, transfer to a 1.00 L volumetric flask, and dilute to the line. Dilution

11

Classification of Analytical MethodsAccording to Size of Sample

<1Ultramicro

<501-10Micro

50-10010-100Semimicro

>100>100Meso

Sample Volume( L)

Sample Weight(mg)

Method

Constituents

<0.1%trace

0.1-1%minor

>1%major

ConstituentsMethod

Page 12: Chapter 1 Introduction(1.00)(0.100)(40.00g NaOH) # g NaOH = -----(1) (1) = 4.00 g NaOH Weigh 4.00 g of NaOH, transfer to a 1.00 L volumetric flask, and dilute to the line. Dilution

12

Solution Terminology

• solute

• solvent

• aqueous solution

• liter

• atomic weight

• molecular weight

Molarity

# moles AMolarity => M = -------------------

# liters solutionor

# millimoles AMolarity => M = -------------------------

# milliliters solution

Page 13: Chapter 1 Introduction(1.00)(0.100)(40.00g NaOH) # g NaOH = -----(1) (1) = 4.00 g NaOH Weigh 4.00 g of NaOH, transfer to a 1.00 L volumetric flask, and dilute to the line. Dilution

13

Useful Algebraic Relationships

wt A (g)# mol A = -----------------

fw A (g/mol)

# mol A = V (L) x M (mol A/L soln)

or wt A (mg)

# mmol A = ----------------- fw A (g/mol)

# mmol A = V (mL) x M (mmol A/mL soln)

Types of Solutions

• strong electrolyte

• weak electrolyte

• non-electrolyte

Page 14: Chapter 1 Introduction(1.00)(0.100)(40.00g NaOH) # g NaOH = -----(1) (1) = 4.00 g NaOH Weigh 4.00 g of NaOH, transfer to a 1.00 L volumetric flask, and dilute to the line. Dilution

14

Useful Algebraic Relationships

n = M ×V

n = W (g)FM(g /mol)

M = nV

(mol /L) Molarity

Formal Concentration

• used for systems which separate (ionize) insolution

• same form for equation as molarity,substitute formula weight for molecularweight for those substances which do notform molecules

Page 15: Chapter 1 Introduction(1.00)(0.100)(40.00g NaOH) # g NaOH = -----(1) (1) = 4.00 g NaOH Weigh 4.00 g of NaOH, transfer to a 1.00 L volumetric flask, and dilute to the line. Dilution

15

Molality => m# moles A

molality => m = ------------------------- # kilograms solvent

• this concentration unit is temperatureindependent as the mass does not changewith temperature whereas volume does

• used in freezing point depression/boilingpoint elevation

• not commonly used.

p-Functions

pX = - log10[X]

examples:

pH

pOH

pCl

pAg

Page 16: Chapter 1 Introduction(1.00)(0.100)(40.00g NaOH) # g NaOH = -----(1) (1) = 4.00 g NaOH Weigh 4.00 g of NaOH, transfer to a 1.00 L volumetric flask, and dilute to the line. Dilution

16

Percent Composition

wt of a solutew - w% = -------------------- 102

wt of solutionvol of a solute

v - v% = -------------------- 102

vol of solutionwt of a solute

w - v% = --------------------- 102

vol of solution

Parts per Million

wt of a solutecppm = ------------------- 106

wt of solution

Page 17: Chapter 1 Introduction(1.00)(0.100)(40.00g NaOH) # g NaOH = -----(1) (1) = 4.00 g NaOH Weigh 4.00 g of NaOH, transfer to a 1.00 L volumetric flask, and dilute to the line. Dilution

17

Parts per Billion

wt of a solutecppb = ------------------- 109

wt of solution

Preparing Solutions

EXAMPLE: Describe the preparation of 1.00L of 0.100 M NaOH solution (f.w.40.00) from reagent grade solid.

Page 18: Chapter 1 Introduction(1.00)(0.100)(40.00g NaOH) # g NaOH = -----(1) (1) = 4.00 g NaOH Weigh 4.00 g of NaOH, transfer to a 1.00 L volumetric flask, and dilute to the line. Dilution

18

EXAMPLE: Describe the preparation of 1.00L of 0.100 M NaOH solution (f.w. 40.00)from reagent grade solid.

(1.00 L soln)# g NaOH = ----------------

EXAMPLE: Describe the preparation of 1.00L of 0.100 M NaOH solution (f.w. 40.00)from reagent grade solid.

(1.00 L soln)(0.100 mol NaOH)# g NaOH = ---------------------------------------

(1 L soln)

Page 19: Chapter 1 Introduction(1.00)(0.100)(40.00g NaOH) # g NaOH = -----(1) (1) = 4.00 g NaOH Weigh 4.00 g of NaOH, transfer to a 1.00 L volumetric flask, and dilute to the line. Dilution

19

EXAMPLE: Describe the preparation of 1.00L of 0.100 M NaOH solution (f.w. 40.00)from reagent grade solid.

(1.00 L soln)(0.100 mol NaOH)# g NaOH = ---------------------------------------

(1 L soln)

EXAMPLE: Describe the preparation of 1.00L of 0.100 M NaOH solution (f.w. 40.00)from reagent grade solid.

(1.00)(0.100 mol NaOH)# g NaOH = ------------------------------

(1)

Page 20: Chapter 1 Introduction(1.00)(0.100)(40.00g NaOH) # g NaOH = -----(1) (1) = 4.00 g NaOH Weigh 4.00 g of NaOH, transfer to a 1.00 L volumetric flask, and dilute to the line. Dilution

20

EXAMPLE: Describe the preparation of 1.00L of 0.100 M NaOH solution (f.w. 40.00)from reagent grade solid.

(1.00)(0.100 mol)(40.00g NaOH)# g NaOH = ----------------------------------------

(1) (1 mol)

EXAMPLE: Describe the preparation of 1.00L of 0.100 M NaOH solution (f.w. 40.00)from reagent grade solid.

(1.00)(0.100 mol)(40.00g NaOH)# g NaOH = ----------------------------------------

(1) (1 mol)

Page 21: Chapter 1 Introduction(1.00)(0.100)(40.00g NaOH) # g NaOH = -----(1) (1) = 4.00 g NaOH Weigh 4.00 g of NaOH, transfer to a 1.00 L volumetric flask, and dilute to the line. Dilution

21

EXAMPLE: Describe the preparation of 1.00L of 0.100 M NaOH solution (f.w. 40.00)from reagent grade solid.

(1.00)(0.100)(40.00g NaOH)# g NaOH = ----------------------------------------

(1) (1)

EXAMPLE: Describe the preparation of 1.00L of 0.100 M NaOH solution (f.w. 40.00)from reagent grade solid.

(1.00)(0.100)(40.00g NaOH)# g NaOH = ----------------------------------------

(1) (1)

= 4.00 g NaOH

Page 22: Chapter 1 Introduction(1.00)(0.100)(40.00g NaOH) # g NaOH = -----(1) (1) = 4.00 g NaOH Weigh 4.00 g of NaOH, transfer to a 1.00 L volumetric flask, and dilute to the line. Dilution

22

EXAMPLE: Describe the preparation of 1.00L of 0.100 M NaOH solution (f.w. 40.00)from reagent grade solid.

(1.00)(0.100)(40.00g NaOH)# g NaOH = ----------------------------------------

(1) (1)

= 4.00 g NaOH

Weigh 4.00 g of NaOH, transfer to a 1.00 Lvolumetric flask, and dilute to the line.

Dilution

#moles solute in conc. soln

equals

#moles solut in dil. soln

therefore

Mconc Vconc = Mdil Vdil

Page 23: Chapter 1 Introduction(1.00)(0.100)(40.00g NaOH) # g NaOH = -----(1) (1) = 4.00 g NaOH Weigh 4.00 g of NaOH, transfer to a 1.00 L volumetric flask, and dilute to the line. Dilution

23

Examples

• 2. How can one prepare 500 mL 1.0 M HClsolution from concentrated HCl solution(12M)?

Examples• 3. What is the molarity of 1:6 (v:v) HNO3

solution?

Page 24: Chapter 1 Introduction(1.00)(0.100)(40.00g NaOH) # g NaOH = -----(1) (1) = 4.00 g NaOH Weigh 4.00 g of NaOH, transfer to a 1.00 L volumetric flask, and dilute to the line. Dilution

24

Examples

• 3. Calculate the molarity of concentratedsulfuric acid (Strength = 95.5-96.5%,Density = 1.84)?

• AAcetic Acid, Glacial, 100% 117 MolarAmmonia, 29% 115 MolarHydrochloric Acid, 37%, 12 MolarNitric Acid, 70%, 16 MolarPhosphoric Acid, 85%, 15 MolarPerchloric Acid, 71%, 11 MolarSodium Hydroxide, 50%, 19 MolarSulfuric Acid, 96%, 18 Molar (36 Normal)

Page 25: Chapter 1 Introduction(1.00)(0.100)(40.00g NaOH) # g NaOH = -----(1) (1) = 4.00 g NaOH Weigh 4.00 g of NaOH, transfer to a 1.00 L volumetric flask, and dilute to the line. Dilution

25

Comparison of Different AnalyticalMethods