Tuesday 30 December 2014

1.2 Kaedah Penyiasatan Saintifik

Kaedah Penyiasatan Saintifik
■ Kaedah Penyiasatan Saintifik

Kaedah sistematik yang dilakukan menurut peraturan dan prinsip saintifik supaya mendapatkan pengetahuan saintifik.
■ Langkah-langkah kaedah penyiasatan saintifik:

Video ini mengandungi maklumat mengenai langkah-langkah kaedah penyiasatan saintifik:

1. Membuat pemerhatian Mengumpul maklumat, mengenai fenomena, menggunakan lima pancaindera.
2. Membuat inferens Membuat kesimpulan awal, atau penjelasan sementara mengenai fenomena berkenaan berdasarkan pemerhatian.
3. Mengenal pasti masalah Masalah dikenalpasti dengan bertanya soalan, berdasarkan kesimpulan yang dibuat.
4. Membuat hipotesis Membuat pernyataan umum tentang hubungan antara pembolehubah yang dimanipulasi dan pembolehubah bergerak balas untuk menerangkan soalan yang ditanya.
5. Mengenal pasti pembolehubah Mengenal pasti pembolehubah dimanipulasikan, bergerak balas dan dimalarkan untuk menguji hipotesis yang dibuat.
6. Mengawal pembolehubah Menentukan cara mengawal pembolehubah yang dipilih, apa yang perlu mengukur dan bagaimana untuk menjaga pembolehubah yang dimalarkan.
7. Merancang eksperimen Senaraikan semua yang diperlukan untuk menyelesaikan eksperimen. Terangkan langkah-langkah butiran siasatan, bagaimana untuk mengumpulkan data.
8. Mengumpul data Membuat pemerhatian atau pengukuran dan kemudian merekodkan data secara sistematik.
9. Mentafsir data Menyusun dan menganalisis data. Pengiraan, graf atau carta yang disediakan untuk mencari sebarang hubungan antara pembolehubah.
10. Membuat kesimpulan Membentuk satu kenyataan mengenai hasil siasatan yang merumuskan apa yang berlaku dalam eksperimen itu, sama ada hipotesis itu diterima atau ditolak.
11. Menulis laporan Satu laporan lengkap bertulis menurut format kaedah penyiasatan saintifik.
■ Animasi berikut menunjukkan aspek yang diperlukan dalam laporan penyiasatan saintifik.

Aktiviti Makmal 1.2.1: Kaedah Penyiasatan Saintifik

Contoh latihan 1.2(a)
Pilih betul [✔] atau salah [✘] untuk kenyataan-kenyataan berikut.
Pernyataan
Penyiasatan saintifik dilakukan melalui satu siri langkah yang sistematik dikenali sebagai kaedah saintifik.
Semua penyiasatan saintifik yang dijalankan mestilah melibatkan data berangka.
Semua hipotesis dapat dibuktikan benar.
Inferen adalah kesimpulan awal yang dibuat berdasarkan pemerhatian awal.
Pembolehubah yang dimanipulasikan merupakan pembolehubah yang digunakan untuk menguji hipotesis.

Contoh latihan 1.2(b)
Padankan langkah-langkah penyiasatan saintifik berikut berdasarkan penjelasan yang diberikan.
Keterangan Kaedah penyiasatan saintifik
Proses membentuk kesimpulan yang logik awal, yang mungkin atau mungkin tidak benar, untuk menerangkan proses pemerhatian. Membuat inferen
Satu proses membuat kenyataan umum yang menyatakan hubungan antara pembolehubah bergerak balas dan pembolehubah yang dimanupulasikan Membuat hipotesis
Satu langkah dalam penyiasatan saintifik supaya maklumat yang disampaikan dengan cara yang lebih bermakna. Menganalisa data
Faktor-faktor atau keadaan yang mempengaruhi faktor-faktor lain dalam penyiasatan. Pembolehubah

Contoh latihan 1.2(c)
Untuk pengaratan berlaku, udara dan air diperlukan. Seorang pelajar menjalankan satu eksperimen untuk mengetahui sama ada udara diperlukan untuk paku besi berkarat. Tentukan pembolehubah yang terlibat dalam eksperimen ini.
Faktor Jenis pembolehubah
Panjang paku besi Pembolehubah yang dimalarkan
Kehadiran atau ketiadaan udara Pembolehubah yang dimanupulasikan
Pengaratan paku besi Pembolehubah yang bergerak balas


⇲ Dapatkan latihan (objektif and subjektif), secara percuma untuk OS Android.

Bab 1: Pengenalan kepada Kimia

Bab 1: Pengenalan kepada Kimia

Isi Kandungan
► 1.1 Kimia dan Kepentingannya
► 1.2 Kaedah Saintifik
► Senarai Video

1.1 Kimia dan Kepentingannya

Maksud kimia
■ Kimia

Kajian saintifik terhadap sifat, komposisi dan struktur bahan-bahan yang terdapat di sekeliling kita.

Perubahan yang berlaku apabila bahan-bahan ini berinteraksi antara satu sama lain.
■ Kimia dan penggunaannya

Kebanyakan aktiviti dalam kehidupan seharian melibatkan tindak balas kimia.

Bahan kimia yang digunakan dalam kehidupan harian yang dihasilkan oleh industri adalah berasaskan kimia.

Bahan kimia Kegunaan
Simen Digunakan sebagai bahan binaan bangunan.
Garam Digunakan dalam masakan.
Digunakan sebagai bahan pengawet makanan untuk membolehkan makanan bertahan lebih lama.
Cat Digunakan untuk melindungi permukaan.
Ejen pembersihan Digunakan sebagai agen pencuci untuk menanggalkan kesan kotoran.
Ubat Digunakan untuk mengubati penyakit.


Kerjaya yang melibatkan bidang kimia

Kerjaya Penerangan
Ahli ekologi
Untuk mengkaji sifat bahan kimia dalam alam persekitaran.
Jurutera genetik
Mengkaji komposisi genetik dalam kromosom dan kesan kejuruteraan terhadap komposisi kromosom.
Geokimia/Geologi
Untuk mengkaji sifat bahan kimia di bumi.
Ahli farmakologi
Mengkaji dan mensintesis ubat-ubatan baru serta  kesan mereka ke atas pelbagai penyakit.

Industri di Malaysia

Bidang Penerangan
Industri petroleum dan gas asli
Menyediakan sumber bahan api untuk kenderaan dan tukang.
Industri kimia
Membuat bahan-bahan petrokimia seperti polivinil klorida atau PVC dan objek plastik seperti baldi dan komponen elektronik.
Industri kimia pertanian
Membuat racun perosak dan baja.
Industri makanan
Menghasilkan bahan tambahan makanan seperti perisa makanan.
Menghasilkan agen pengawet seperti sodium benzoate.
Industri farmasi
Menghasilkan dan memasarkan ubat berlesen untuk digunakan sebagai ubat-ubatan.
Industri elektronik
Menghasilkan mikrocip daripada semikonduktor seperti silikon dan seramik.
Menghasilkan superkonduktor untuk memproses maklumat dengan lebih cepat.

Contoh latihan 1.1(a)
Isikan tempat kosong dengan jawapan yang tepat.
(a) __________Kimia adalah satu bidang kajian yang berkaitan struktur, komposisi, sifat dan interaksi jirim.
(b) __________Ahli farmasi memerlukan kedua-dua bahan kimia dan ilmu perubatan untuk menemui ubat-ubatan baru bagi menyembuhkan penyakit.
(c) __________Geokimia terlibat dalam penyelidikan kimia di dalam kerak bumi.
(d) __________Industri berasaskan kimia menghasilkan pelbagai produk yang berguna untuk pengguna dan menyumbang kepada pembangunan ekonomi negara.


⇲ Dapatkan latihan (objektif and subjektif), secara percuma untuk OS Android.

2.1.1 Laboratory Activity : Investigating the diffusion of particles in a gas, liquid and solid

Laboratory Activity 2.1.1:
Investigating the diffusion of particles in a gas, liquid and solid
Aim: Investigating the diffusion of particles in a gas, liquid and solid
Hypothesis : Diffusion takes place in a gas, liquid and solid. The rates of diffusion in a gas, liquid and solid are in decreasing order.
Problem statement: Investigating the diffusion of particles in a gas, liquid and solid
Variable:

» Fixed variable: Temperature

» Manipulated variable: Medium of diffusion

» Responding variable: Rate of diffusion
Material:
» Liquid bromine
» Potassium permanganate crystals
» Water
» Hot jelly solution
Apparatus:
» Two gas jars with plastic covers
» Petri dish
» Teat pipette
» Spatula
» Rubber stopper
» Boiling tube


Procedures:

(A) Diffusion in a gas
1. The animation below shows the arrangement and the results of the experiment.
2. A few drops of liquid bromine are dropped into a gas jar using a teat pipette.
3. The gas jar is covered with a gas jar cover.
4. Another gas jar is placed upside down on top of the first jar.
5. The cover is removed and any colour change is recorded.
6. The time taken for the brown bromine vapour to spread into the second gas jar is recorded.

(B) Diffusion in a liquid
1. The animation below shows the arrangement and the results of the experiment.
2. A petri dish is filled with water.
3. A few potassium permanganate crystals are placed at the bottom of the water using a spatula.
4. Any colour change is recorded.
5. The time taken for the purple permanganate ions to spread throughout the water is recorded.

(C) Diffusion in a solid
1. The animation below shows the arrangement and the results of the experiment.
2. Some freshly cooked jelly solution is placed into a boiling tube until it is almost full.
3. The jelly is allowed to set.
4. A small potassium permanganate crystal is placed on top of the jelly.
5. The boiling tube is then stoppered using a rubber stopper.
6. Any colour change is recorded.
7. The time taken for the purple permanganate ions to spread throughout the solid jelly is recorded.
Discussion:

Diffusion has taken place in the gas (air in experiment A), liquid (water in experiment B) and solid (jelly in experiment C).

The rates of diffusion of the particles in the solid, liquid and gaseous states differ. It is highest in gases, lower in liquids and the lowest in solids.

This shows that there are more and bigger spaces between particles in the gas. The spaces between liquid particles are smaller. The particles in the solid state are very close with little space between them.

The occurrence of diffusion proves that matter (bromine and potassium permanganate) consist of particles in constant motion

The diffusion experiments show that particle posses the kinetic energy and are in constant motion.
Conclusion:

Bromine is made of tiny and discrete particles.

Potassium permanganate is made up of tiny and discrete particles (ions).


⇲ For exercise(objective and subjective), download for free on Android OS.

Monday 29 December 2014

1.2 Scientific Method

Scientific Investigation Methods
■ Scientific investigation methods

Systematic method that performed following rules and scientific principles to obtain scientific knowledge.
■ Steps of Scientific investigation method:

This video contains information about steps of scientific investigation method:

1. Making observation Gathering information, about a phenomenon, using our five senses.
2. Making inference Making early conclusion, or tentative explanation, about the phenomenon, based on the observation.
3. Identify problem Problem is identified by asking question, based on the inference made.
4. Making hypothesis Making a general statement on the relationship between a manipulated variable and a responding variable in order to explain the question asked.
5. Identifying variables Identifying the manipulated, responding and fixed variables of an experiment to test the hypothesis made.
6. Controlling variables Deciding how to manipulate the chosen variable, what to measure and how to keep the fixed variables constant.
7. Planning an experiment List everything needed to complete the experiment. Describe details steps of investigations, how to collect the data.
8. Collecting data Making observations or measurement and then recording the data systematically.
9. Interpreting data Organising and analysing data. Calculations, graph or charts may be drawn to look for any relationship between the variables.
10. Making conclusion Forming a statement on the outcome of an investigation that sums up what happened in the experiment, whether the hypothesis was accepted or rejected.
11. Writing report A complete report is written according to the format of the scientific investigation method.
■ The animation below shows the items to be included in a scientific investigation report.

Laboratory Activity 1.2.1: Scientific Investigation method

Worked-example 1.2(a)
Choose true [✔] or false [✘] for the statement given.
Statement
Scientific investigation is done through a series of systematic steps called scientific methods.
All scientific investigations conducted must involve numerical data.
All hypothesis can be proven true.
An inference is the initial conclusion that is made based on the beginning observation.
Variables that are manipulated are variables that are used to test the hypothesis.

Worked-example 1.2(b)
Match the following scientific investigation steps based on the explanation given.
Explanation Scientific investigation method
A process of forming an initial logical conclusion, which may or may not be true, to explain a process or observation. Making inference
A process of making a general statement that states the correlation between the responding variable and the manipulated variable. Making hypothesis
A step in a scientific investigation in which information is presented in a more meaningful way. Analizing data
Factors or conditions which influence other factors in an investigation. Variables

Worked-example 1.2(c)
For rusting to take place, air and water must be present. A students carry out an experiment to find out whether air is required for an iron nail to rust. Determine the variable involved in this experiment.
Variables Types of variable
The length of iron nail Constant variable
Presence or absence of air Manipulated variable
Rusting of iron nail Responding variable


⇲ For exercise(objective and subjective), download for free on Android OS.

1.2.1 Laboratory Activity : Scientific Investigation method


Laboratory Activity 1.2.1:
Scientific Investigation method
Aim: Investigating the effect of the temperature of water on the solubility of sugar
Problem statement: Does the amount of sugar that dissolve in water increase when the temperature of water increase?
Hypothesis: The higher the temperature of the water, the greater the mass of sugar that dissolve in it.
Variable:

» Fixed variable : Volume of water and size of sugar

» Manipulated variable : Temperature of water

» Responding variable: Amount of sugar that dissolves at different temperatures
Material:
» Sugar
» Water
Apparatus:
» 100 ml measuring cylinder
» 250 ml beaker
» Electronic balance
» Bunsen burner
» Tripod stand
» Wire gauze
» Spatula
» Thermometer
» Glass rod
Procedures:

The animation below shows the arrangement and the results of the experiment.

1. 100 cm³ of water is measured using a measuring cylinder and is poured into a 250 cm³ beaker.
2. The temperature of the water is recorded using a thermometer.
3. 100 ml beaker is filled with sugar. The beaker and its contents are then weighed and recorded as a gram.
4. The water is added a little at a time to the 100 cm³ of water in the beaker using a spatula. The mixture is then stirred using a glass rod.
5. The process is continued until no sugar can further dissolve in the water.
6. The beaker and its sugar content is weighed again and recorded as b gram.
7. The amount of sugar that dissolved in the water at room temperature is (a - b) gram.
8. The experiment is repeated by heating the water to temperatures of 40 ºC, 50 ºC, 60 ºC and 70 ºC respectively.
Results:

Temperature (ºC) Room temperature 40 50 60 70
Initial mass of beaker and its contents(g) a b c d e
Final mass of beaker and its contents(g) b c d e f
Mass of sugar dissolve(g) a-b b-c c-d d-e d-f

A graph of the mass of sugar dissolved against temperature is plotted.
Conclusion: The amount of sugar that dissolves in the water increases when the temperature of the water increases. The hypothesis is accepted.


⇲ For exercise(objective and subjective), download for free on Android OS.

3.3 Number of Moles and Mass

Number of moles and mass
Definition : Molar mass: The mass of a substance that contains one mole of the substance.

Molar mass of substance = mass of 1 mole of substance

Molar mass of substance = mass of substances for 6.02×1023 particles.
■ Relationship between the number of moles, the mass molar and the mass of a substance.

Molar mass of a substance is equivalent to their relative atomic mass or relative molecular mass or relative formula mass written in the unit of gram.

For example:
The relative atomic mass of nitrogen, N = 14, thus the molar mass of nitrogen atom is 14g.
The relative molecular mass of nitrogen, N2 = 14 x 2 = 28, thus the molar mass of a molecule = 28g.
■ Summary of relationship between the number of moles, the mass molar and the mass of a substance.
Worked-example 3.3(a)
Calculate the number of particle in

(a) Calculate the mass of 0.5 mole chlorine Cl2 [RAM : Cl = 35.5]

Solution
The mass of 0.5 mole Chlorine Cl2
Number of moles =Mass of Chlorine Relative molecular mass
0.5 =Mass of Chlorine 2.0×35.5
Mass of Chlorine = 0.5×71
Mass of Chlorine = 35.5g

(b) Find the number of moles in 32g Copper, Cu. [RAM : Cu = 64]

Solution
Number of moles =Mass of Copper Relative molecular mass
Number of moles =32 64
Number of moles = 0.5mol

Worked-example 3.3(b)
Calculate the number of particles in 20g Methane, CH4 , [RAM: H = 1, C = 12]

Solution
Number of moles =Mass of Methane Relative molecular mass
Number of moles =20 12+(4×1)
Number of moles = 1.25mol
Number of particles = Number of moles × Avogrado constant
Number of particles = 1.25×6.02×1023
Number of particles = 7.75×1023


⇲ For exercise(objective and subjective), download for free on Android OS.

3.2 The Mole and the Number of Particles

The number of moles and the number of particles
Definition : Mole: One mole is the amount of any substance which contains the same number of particles as there are in 12g of Carbon-12, that is 6.02×1023 or the Avogrado constant.
■ Relationship between number of moles and number of particles.

1 mole of any substance contains 6.02×1023 particle of that substances (atoms, molecules or ions).

For atom :
1 mole of lithium (Li) : 6.02×1023 atoms of lithium
1 mole of carbon (C) : 6.02×1023 atoms of carbon

For molecule:
1 mole of hydrogen ( H2 ) : 2×6.02×1023 atoms of hydrogen or 6.02×1023 molecules of hydrogen.
1 mole of carbon dioxide ( CO2 ) : 3×6.02×1023 atom or 6.02×1023 molecules of carbon dioxide.


For ion:
1 mole of sodium chloride (NaCl) : 6.02×1023 ions Na+ and 6.02×1023 ions Cl-
1 mole of zinc bromide ( ZnBr2 ) 6.02×1023 ions Zn+ and 2×6.02×1023 ions Br-

■ Summary of relationship between number of moles and number of particles.
Worked-example 3.2(a)
Calculate the number of particle in

(a) 0.5 mole of Copper

Solution
Number of particle in 0.5 mole of copper
=0.5×6.02×1023
=3.01×1023 atom

(b) 0.25 mole Lead(II) ions, Pb2+

Solution
Number of particle in 0.25 mole of Lead(II) ions,
=0.25×6.02×1023
=1.505×1023 ion Pb2+

(c) 3.0 moles Carbon Dioxide,

Solution
Number of particle in 3.0 moles of Carbon Dioxide
=3.0×6.02×1023
=1.806×1024 molecule CO2

Worked-example 3.2(b)
Calculate the number of moles of the following substances

(a) 1.505×1024 atom of Silver, Ag

Solution
Number of moles
=1.505×1024 6.02×1023
= 2.5 mol

(b) 3.01×1022 Oxide ions, O2-

Solution
Number of moles
=3.01×1022 6.02×1023
= 0.5 mol

(c) 4.515×1024 Nitrogen molecules, N2

Solution
Number of moles
=4.515×1024 6.02×1023
= 7.5 mol of molecules N2


Worked-example 3.2(c)

(a) Find the number of atoms in 1.5 moles of Cl2

Solution
1.5 =Number of molecules 6.02×1023
Number of molecules = 1.5×6.02× 1023
Number of molecules = 9.03×1023
Number of atom = 2×9.03×10 23
Number of atom = 1.806×1024 atom

(b) Find the number of ions in 0.5 mole of Magnesium Chloride, MgCl2

Solution
0.5 =Number of particles 6.02×1023
Number of particles = 0.5×6.02× 1023
Number of particles = 3.01×1023
Number of ions = 3×3.01×1023
Number of ions = 9.01×1023


⇲ For exercise(objective and subjective), download for free on Android OS.

Monday 22 December 2014

3.1 Relative Atomic Mass and Relative Molecular Mass

Relative atomic mass
■ Relative atomic mass based on Carbon-12 scale [modern standard]

Definition : The number of times the mass of atom is greater than 112 of the mass of a carbon-12 atom.
Relative atomic mass = Mass of atom of substance 112 × mass of carbon-12 atom 

For example : A magnesium atom is 24 times greater than 112 of the mass of a carbon-12 atom, thus the relative atomic mass of magnesium is 24.
Relative atomic mass of magnesium
=24×112 ×r.a.m of carbon-12
=24×112 ×12
=24

The animation below shows the idea of relative atomic mass in details.
■ Relative atomic mass of several elements :

Element Symbol Relative Atomic Mass
Hydrogen H 1
Helium He 4
Carbon C 12
Nitrogen N 14
Oxygen O 16
Sodium Na 23


Relative Molecular Mass
■ Relative molecular mass based on Carbon-12 scale

Definition : The number of times the mass of a molecule is greater than 112 of the mass of a carbon-12 atom.
Relative molecular mass =Mass of molecule of substance112 × mass of carbon-12 atom 

For example : One nitrogen molecule (N2)is 28 times greater than 112 of a carbon-12 atom, thus, the relative molecular mass of nitrogen is 28.

■ Calculation of relative molecular mass :

Adding the relative atomic masses of all the atoms of the elements forming the molecule.
This video gives the idea about relative atomic mass and relative molecular mass.

Worked-example 3.1(a)
Calculate the relative molecular mass for the following elements:
(Relative atomic mass : H:1; C:12; N:14; O:16)

Solution
Element Molecular Formula Relative Molecular Mass
Nitrogen N2 14×2=28
Water H2O (1×2)+16=18
Glucose C6H12O6 (12×6)+(1×2)+ (16×6) =180


Relative Formula Mass
■ Relative molecular mass based on Carbon-12 scale

Definition : The number of times the mass of an ionic substances is greater than 112 of the mass of a carbon-12 atom.
Relative formula mass =Mass of an ionic substance112 × mass of carbon-12 atom 

■ Calculation of relative formula mass :

Adding the relative atomic masses of all the atoms of the elements forming the substances.
Worked-example 3.1(b)
Calculate the relative formula mass for the following substances:
(Relative atomic mass : H:1; C:12; O:16, Mg:24, S:32, Cl:35.5, Ca:40, Cu:64)

Solution:
Element Compound Formula Relative Formula Mass
Copper Chloride CuCl2 64+ (35.5×2) =135
Calcium Carbonate CaCO3 40+12+ (16×3) =100
Magnesium Sulphate Dehydrate MgSO4.7H2O 24+32+ (16×4)+ 7{(1×2)+16} =246



⇲ For exercise(objective and subjective), download for free on Android OS.