Chapter 1 Measurements
Some important units of measurement
1-1.
SI units
(Le Système International d'Unités):
• International System of Units (국제단위계)
• 1960년 제 11차 국제도량형총회(CGPM, Conférence Générale
des Poids et Mesures)에서 명칭과 약칭 "SI"를 채택 결정
• 7개의 기본 물리량, 이름, 기호 선정
Using prefixes as multipliers
Rather than using exponential notation, we often use prefixes from Table 1-3 to express large or small quantities.
Converting between units
Although SI is the internationally accepted system of measurement in science, other units are encountered.
Useful conversion factors are found in table 1-4.
1-2.
chemical concentrations
1. The mole
▶ 약자는 mol 임
▶ 화학종이 아보가드로수 (6.022 Х 1023 개) 만큼 있으면 1mol
▶ 몰질량 (molar mass, M)은 화학종 1mol의 질량 (단위, g)
nx: X의 몰수 (mol),
Mx: X의 몰질량 (g/mol)
massx: X의 질량 (g)
▶ X의 몰수(moles)
▶ X의 밀리몰수 (mmoles)
Ex) 분자의 몰질량(M) 계산: 원자질량을 모두 합한 다음 g을 붙임.
Formaldehyde(CH2O) 및 glucose(C6H12O6)의 몰질량?
Solutions and their concentrations
Molar concentration (c, molarity): 단위 (M, mol/L)
■ Analytical molarity (분석몰농도, mol/L)
■ Equilibrium molarity (평형몰농도, mol/L)
(at equilibrium)
▶ [ ] 기호를 사용하여 표시하기도 함
Percent concentration (%)
Solution
= solute + solvent
Parts per million (ppm) and parts per billion (ppb)
Parts per million parts billion
Sometimes, composition is expressed as parts per million (ppm) or parts per billion (ppb),
which mean grams of substance per million or billion grams of total solution or mixture.
1-3 preparing
solutions
To prepare a solution with a desired molarity from a pure solid or liquid,
we weigh out the correct mass of reagent and dissolve it in a volumetric flask ( figure 1-3)
Solution-diluent volume ratios
(용액-묽힘 부피비)
진한용액의 부피 : 묽히는 용액의 부피 = A : B
⇒ 1 : 4 HCl 용액 = 진한 HCl 부피 1 + 4 부피의 물
p-function
Stoichiometric calculations
2 mol
1 mol
1 mol
2 mol
⇒ 양론계수가 맞추어진 화학방정식은 반응물과 생성물의
몰비에 대한 정보를 제공
1-4 Stoichiometry calculations for Gravimetric Analysis
Chemical analysis based on weighing a final product is called gravimetric analysis.
1-5.
introduction to titrations
Procedures in which we measure the volume of reagent needed to react with
analyte (the sub-stance being measured) are called volumetric analysis.