탄자니아에서의 화학 수업교안(Mole concept and calculation)

FORM3 수업용 교안 입니다.

이번 교안은 금년에 실제로사용한 내용입니다. CHAPTER 4  The Mole concept and Related Calculations로서 중학교 3학년학생들에게 가르쳐야 하는내용인데, 교과 내용이 어려워 주어진 시간에 가르치기 힘든 단원입니다. 가르치면서 느낀 점은 학생들이 영어를 잘 하지 못하는데다 화학 용어를 제대로 이해 하지 못해 어려움이 따르는 단원입니다. 칠판에 쓰고 가르치려니 넘 힘들어서 만들어 보았습니다.  참고 하세요.

CHAPTER 5 VOLUMETRIC ANALYSIS - HOW to make a STANDARD SOLUTION and Titration 도 함께 넣어봅니다. 

chapter 4. The Mole concept and Related Calculations

◎ This page is the first page of chapter 4

<Contents>

4.1 The mole as a unit 4.2 Molar mass

4.3 Molar volume of gases 4.4 Number of particles in a given amount of substance

4.5 The mole in stoichiometric calculations

4.6 Molar concentrations

Learning objectives

* By the end of this chapter, you should be able to:

1. compare the mole with other units of measurement

2. measure the molecular quantities of different substances

3. convert known masses of element, molecules or ions to moles

4. convert known volumes of gases at S.T.P to moles

5. convert known masses of solids and gases to actural numbers of particles

6. prepare molar solutions of various soluble substances

7. do simple calculations based on the mole concept and balanced chemical equations

Useful terms * mole * Avogadro’s number * relative atomic mass * relative molar mass * molar volume * Avogadro’s law * Avogadro’s constant * molar solution * molar mass * molarity * concentration * stoichometry

4.1 The mole as unit of measurement

Objects are grouped and counted in unit amounts. For example, we buy a gross of chalk, a pair of socks a crate of soda or beer, etc.

1 pair= 2 articles, 1dozen= 12 articles,

1 gross= 12dozens=(12×12)articles

 

1mole=6.02×1023 particles The small particles, e.g. atoms, electrons, molecules, ions are counted in moles 1mole of atoms =6.02×1023 atoms 1mole of molecules =6.02×1023 molecules

The mole is the amount of substance that contains as many elementary particles as there are atoms in 12g of carbon-12 isotope.

The mass of an atom of carbon is 1.993×10-23g. So the number of atoms 12g of carbon is given by: 12g/1.993×10-23 or about 600 000 000 000 000 000 000 000 atoms

 

Therefore, a mole is a very large number. It is called the Avogadro’s constant(symbol: L or NA) in memory of the contribution made by Italian scientist, Amedeo Avogadro (1776-1856).

L=6.02×1023 mol-1

One mole of any substance contains as many elementary particles as the Avogadro’s constant.

 

* Relationship between mass and mole

the mass of one mole of atoms of any element expressed in gram. For example:

1 mole of sulphur atoms weighs 32g

1 mole of oxygen atoms weighs 16g. But 1 mole 1 mole of oxygen molecules(O2) weighs 32g

 

* Relative formula mass and mole

For example the relative formular mass of Sodium hydroxide(NaOH) is:

NaOH=23+16+1=40 (*Notice that: There is no unit)

 

4.2 Molar mass

The molar mass of a substance is the mass of one mole of that substance. Molar mass is expressed in grams per mole(gmole-1).

For example: The molar mass of ;

(i) Sodium hydroide(NaOH) is 40g

(ii)Hydrochloric acid(HCl)= (1×1)+(1×35)=36g

Number of moles=Mass of substance/Molar mass

 

4.3 Morlar volumes of gases

All gases containing 6.02×1023molecules will occupy the same volume at fixed temperature and pressure. At 0℃ and 1 atmosphere pressure, 1mole of any gas occupies 22.4dm3 or 22400cm3.

Consider the following example

1 mole of O2 molecules occupies 22.4dm3 at S.T.P ∴ (16×2)g of O2 molecules occupies 22.4dm3 at S.T.P

1 mole of NH3 molecules occupies 22.4dm3 at S.T.P

∴ (14+3)g of NH3 molecules occupies 22.4dm3 at S.T.P

* 교육단원 여러분! 제 개인 생각인데, 처음 이곳에 와서 어떻게 가르쳐야 할지 감이 잡히지 않았습니다. 교과서도 없고, 가르치라는 교육과정(실라부스)만 있는 상태였습니다. 가르쳐야 할 내용은 상당히 많고, 때론 수준높아 과연 중3학년에 해당하는 학생들이 이해 할 수있을까하는 의구심이 많이 들었습니다. 1년 지나면서 교재를 재구성해야 할 필요를 느낍니다만.....! 혼자하는 것보다 우리 단원들이 각자 수업한 자료들을 올려놓으면 필요한 단원들이 재구성하여 사용하면 좋으리라 판단됩니다. 올려주시는 자료들은 처음에 오신 코이카 단원들에게 큰 도움이 되리라 생각됩니다. 우리가 봉사하러 왔으니, 새로오시는 분들에게 정보를 드리는 것도 봉사가 아닐까하는 생각에 글을 올려 봅니다.