Structure of an Atom

Isotopes

Isotopes are atoms of the same element which have same proton number but different number of neutron and therefore also a different mass number.

https://youtu.be/1wGrkVb_rZY

Capacitor and Capacitance

Coulomb's law

How to draw a simple circuit diagram?

Easiest way to make a motor

Electrolysis

Wireless electricity

Density

Diffusion

Electromagnetic Induction

Electromagnet

রচনা - কামরুল আলম

Answer of Edexcel AS Chemistry Student’s Book

Direct Download Answer of Edexcel AS Chemistry Student’s Book

Edexcel International AS Chemistry

Direct download link for Edexcel AS Chemistry Unit-1 , Edexcel AS Chemistry unit 1, Collection of Formulae, Equation & Amount of substance (Jan 2013-June-2014) Related past question. You will get an idea about the type of question.
1.3 Formulae, Equation & Amount of substance (Jan 2013-June-2014)

Edexcel International AS Chemistry- Unit-3B

Here are some topics you should know for Chemistry Unit 3B exam.

• Test for Halides
• Flame tests
• Preparation of aldehydes using simple distillation and carboxylic acids by heating under reflux
• Preparation of halogenoalkanes
• Test for alkenes using bromine water and acidified potassium per manganate
• Test for halide present in a halogenoalkane by warming with sodium hydoroxide dissolved in ethanol followed by dilute nitric acid (to neutralize OH) and silver nitrate followed by ammonia solution
• Distinguish between aldehydes and ketones using Benedicts or Fehlings solution. Formation of red precipitate confirms aldehyde
• Drawing apparatus for simple distillation, heating under reflux and seperation of two immiscible liquids (dropping funnel)
• Test for sulfates, sulfites and carbonates using barium chloride solution
• Energetics: Enthalpy of neutralisation, combustion and displacement
• Rates of reaction
• Chemical equilibria
• Reactions of group 2 and group 7 elements
• Volumetric analysis: esp thiosulfate
• Test for SO2, CO2, H2 and O2. (by sankait36): SO2 - turns acidified potassium dichromate(VI) from orange(Cr6+) to green(Cr3+), CO2 - turns lime water milky (due to insoluble calcium carbonate), H2 - test with burning splint, ignites with a pop sound, O2 - relights a glowing splint
• Uncertainties (by sankait36): uncertainty = (maximum reading) - (minimum reading) / 2 , %uncertainty = (uncertainty / actual reading) * 100
• In titration, discard the titre that is not concordant to 0.2 cm^

Color of Indicators

Color of Indicators

Indicator	Colour in strong acid	Colour in weak acid	Colour neutral	Colour in weak alkali	Colour in strong alkali
pH	1-3	4-6	7	8-10	11-14
universal	red	orange/yellow	green	blue	purple
methyl orange	red			yellow	yellow
phenolphthalein	colourless	colourless			pink
litmus	red	red		blue	blue

Top of Form

Bottom of Form

Investigating alkanes and alkenes

IGCSE Chemistry

section 3 

  

Investigating alkanes and alkenes

 

Part A: Comparing combustion of an alkane and an alkene - demonstration

1.    Put a few drops of hexane (an alkane) on a watch glass or in an evaporating basin.

2.    Make sure the bottle is well away, then, ignite the liquid (preferably in a fume cupboard).

3.    Repeat this using hexene (an alkene).

Questions

1.    Describe the colour of the flame when hexane was burning

2.    Was there any difference between the alkane and alkene?

3.    Write a word equation for the complete combustion of hexane

4.    What is the black substance visible at the top of each flame and why is it formed?

5.    Write a word equation for the reaction in question 5

6.   What is the environmental impact of burning alkanes?

Part B: Using bromine water

1.    Place two small clean dry test tubes into your test tube rack.

2.    Place approximately 2 ml of the hexane into the first test tube and one ml of hexene into the second.

3.    Add 5 drops of the bromine water into each of the two samples, taking care to not breath the bromine vapor or spill the bromine on your skin.

4.    Cover each test tube with a bung and, with your finger on the bung, shake each test tube. 

5.    Record any colour changes i.e. colour before and after the addition of the bromine water in a table.

Questions

1.    In which test tube did an immediate reaction take place?  Give a reason for your answer.

2.    What reaction took place in the test tube you answered in (1)?

3.    Write a word equation and balanced symbol equation for the reaction.

4.    Could we use bromine water to find out if a hydrocarbon is an alkane (saturated) or an alkane (unsaturated). Explain your answer.

Part C: Using potassium manganate

Repeat steps 2 to 5 with both hexane ands hexane but using potassium manganate. Record your observations in a table

Questions

1.    In which test tube did an immediate reaction take place?  Give a reason for your answer.

2.    Could we use potassium manganate to find out if a hydrocarbon is an alkane (saturated) or an alkane (unsaturated). Explain your answer.