Nuclear Equations in universal context

Prepare yourself for a boring huge chunk of text...

·         Hydrogen is the most common element in the universe, ever. This is due to its very simple structure.

·         Formation of new element takes place in dense gas clouds. (Model)

·         Dense gas clouds are constantly “swirling and moving”.

·         Generally, atoms in the dense clouds may become plasma.

·         Plasma is a mixture of atoms, ions and electrons.

·         Lighter elements form heavier ones in dense gas clouds via fusion.

·         The temperature of gas clouds can vary between 10 and 100 Kelvin. We know this via replicating the reactions that occur in the clouds.

·         Gas clouds do not have a constant density.

·         There’s a gravitational field in the centre of clouds forming great temperature and pressure at the core.

·         Fusion is the joining of 2 nuclei.

·         When fusion occurs, energy is released, provoking more fusion to occur. However this is not classed as a chain reaction.

·         First reactions in gas clouds often include fusion of Hydrogen forming Helium, releasing gamma.

²H₁ + ³H₁ >> ⁴He₂ + g

·         Fusion can occur between any nuclei.

·         Heavy weight stars have higher temperatures because as they’re heavier, they have a greater gravitational field making them a better element manufacturer.

·         The reason cores are FE is because Iron production doesn’t release any energy as a bi product in order to provoke further fusion to occur.

·         Bigger stars are unstable and may cause SuperNovas.

·         Our sun is a light weighted star.

Nuclear Equation Summary

AS Level students must be able to read and interpret Nuclear equations.

A few examples:

Notes on nuclear reactions

· Nuclear reactions are reactions that involve the nucleus, while chemical reactions only involve the electrons in an atom.

· Isotope: Atom with an unusual amount of neutrons.

· RadioIsotopes are isotopes that are radioactive. Those are quite useful in medicine and geology.

· Radio Activity is spountanious!

· Radiation types are Alpha, Beta and Gamma.

Fuel Density

... Because no one cares about moles in the real world.

Energy density is the energy given out when 1 Kilogram of a certain fuel is consumed.

E.g. Ethanol is C₂H₅OH = 46

Delta H = -1367 Kilo joules per mole (Based on a calorimeter experiment)

Delta H = -1367/ 46 = -29.717 Kilo joules per gram.

Delta H = -29.717 x 1000 = -29717 Kilo joules per 1 Kilogram

Radio Isotopes

Radio Isotopes are Decaying isotopes, therefore they're radioactive, hence the name.

· We can use Radio Isotopes to date rocks in Geology.

· We can use Radio Isotopes in tumour treatment in medicine.

· We can use Radio Isotopes in dating any Carbon-based object. (Carbon 14)

Geology

We can date Igneous rocks using Radio Isotopes. Often Potassium 40. It has the half life of 1.3 × 10⁹ years.

Archean age is not the same as the age of the earth! (Not to be confused)

For Radio Isotope Dating to work:

1. Half life must be known accurately.

2. There must be no movement of isotopes in or out of the rocks since formation.

3. The clock cannot be reset by metamorphism.

Medicine

The ratio of Carbon 12 to Carbon 14 is stable in living organisms. This stops when productivity stops, so we can estimate the time of death.

The half life of Carbon 14 is 5730 years.

We use Gamma to destroy cancerous cells.

Iodine is a radioactive isotope that we can use in medicine, it’s a gamma emitter.

We usually use Gamma in medicine because it’s the least Ionising of three types of radiation, which results in the smallest amount of cell deformation possible.

Nuclear Fusion Summary

· ... Requires a large amount of energy.

· ... Is when lighter nuclei join to make a bigger nucleus.

· High temperatures are needed, similar to those in stars; this is because the nuclei initially repel each other due to magnetic charge.

· The energy released is higher than the energy put in the fusion.

Nuclear Fusion might be slightly confusing at first. In GCSE we were taught balancing equations. Whatever's put in, must come out. While in Nuclear Fusion equations, this isn't true.

For example:

²H₁ + ³H₁ → ⁴He₂ + ¹e₀

Half-Life - Decay and all that

Half Life

... Is the time for half the atoms in a radioactive substance to disintegrate.

... Is useful as a measurement in Medicine and Geology.

... Is what’s measured in Carbon 14 dating.

... Varies greatly from an element to another.

...Is different in various isotopes, even if they belong to the same element.

Enthalpy – Continued

Δ H = Mass of Water x Specific heat capacity x θ of water

E.g.

0.21 g of Ethanol was used to heat 100 g of water.

The water’s temperature increased by 10 Celsius.

Δ H = Mass of Water x Specific heat capacity x θ of water

Δ H = 100 x 4.18 x 10

Δ H = 4.18 Kilo Joules

We can use this method to find out the enthalpy in a mole of the substance:

E.g. Knowing that 0.31 g of Ethanol gave 4.18 Kilo Joules of energy:

We divide by the mass and multiply by the molecular mass of the substance.

Δ H = 4.18 Kilo Joules ÷ 0.31 × 46

Δ H = 620.26 Kilo Joules

n.b. Don’t forget to use BASE UNITS before doing any calculation.

A brief lesson in Greek!

· Delta, Δ is the symbol for “Change” in a value.

· Theta, θ is the symbol for “Change” in a heat value.

· H, is the symbol for Enthalpy!

Recap on Atom Structures

J. Dalton defied the atom.

We only have models of the atoms, no one’s “really sure”.

Atoms have equal amounts of electrons and neutrons, otherwise they’re Isotopes.

Necessary knowledge:

· Netrons have a mass of 1.

· Protons have a mass of 1. And are positively charged.

· Electrons have a mass of 0.00055. And are negatively charged.

Despite that electrons are what’s more involved in chemical reactions, chemists are also interested in the nucleus, where protons and neutrons are, because they define and guide what the element of the atom is, or if it’s an isotope.

Isotopes have different amount of neutrons, so they have the same charge as their father element. So, not to be confused with ions.

Some Isotopes are referred to as Radio Isotopes, because we use them in Radiology examinations, as they can be digested and tracked around the body. Examples include ⁴⁸Calcium & ⁹⁰Strontium.

- Periodic table guide!

Protons and electrons are the small number.

Neutrons is the big number, take away the small one. If not equal to small number, then it’s an isotope.

We can find the RAM of an atom via knowing the quantities of it's isotopes in a specific setting, we then multiply each isotope's number with its percentage quantity, add them up, and divide by a hundred. For example:

Q. What is the relative atomic mass of Chlorine, if it contained 75% Cl³⁵ and 25% Cl³⁷?

((75 x 35) + (25 x 37)) / 100 = 35.5

Activation Enthalpy (Setting stuff on fire)

X is endothermic because the energy produced is lower than the energy of the reactants added.

Y is exothermic because the energy produced supersedes the energy of the reactant added.

Notes:

·         We add activation enthalpy to fuel to break bonds, creating new product.

·         If we get more energy than we put in, reaction is exothermic, which is good in the case of fuels.

·         The reactant energy required is whatever energy is required to break the bonds in the solution/fuel. For example, in the case of Methane:

Methane reaction formulae:

  CH₄ + 2O₂  à CO₂ + 2H₂O

4 C-H bonds + 2 O=O bonds à 2 C=O bonds + 4 H-O bonds

4(414) + 2(498) à 2(720) +4(464)

Previously knowing that:

C-H bonds require 414 K.joules mole^-1 to break/make.

O=O bonds require 498 K.joules mole^-1 to break/make.

C=O bonds require 720 K.joules mole^-1 to break/make.

O-H bonds require 464 K.joules mole^-1 to break/make.

Which results in:

2652 K.joules mole^-1  à  3296 K.joules mole^-1

Meaning, the reaction of reacting Methane with Oxygen is exothermic.

Cyclo Alkanes

… are alkanes that do not follow the general formulae, as they have no end and no beginning in the chain, as they take a circular structure.

Such as Cyclohexane C₆H₁₂

_N.b. 

·         Peptane & Octane are the main components in fuel.

·         The longer the Hydrocarbon chain, the less volatile it is.

·         The shorter the Hydrocarbon chain, the lower its Flash point.

Developing Fuels: Unorthodox Hydrocarbons

Some Hydrocarbons don’t follow the general formulae.

Hydrocarbons are categorised according to the longest chain available in the compound.

For example:

This Butane that has 5 Carbons, and 12 Hydrogens.

It is still considered a butane, as its longest chain holds four Carbons.

To include the new added Carbon, it is called a Methyl-Butane.

We refer to it as 2 – MethylButane to indicate that the added Carbon branches off the 2^nd carbon in the longest chain.

Starter Exercise: Calculating the molecular mass

Calculate the molecular mass for each of the following:

·         Ethane

C₂H₆

C=12

H=1

C × 2 = 24

H × 6 = 6

24+6 = 30

·         Benzene

C₆H₆

C=12

H=1

C × 6 = 72

H × 6 = 6

72+6 = 78

·         Cobalt (II)

CoCl₂

Co = 59

Cl = 35.5

Cl × 2 = 71

59+71 = 130

·         Potassium Permanganate

KMnO₄

K = 39

Mn = 55

O = 16

O × 4 = 64

39+55+64 = 158

·         Ammonium Sulphate

(NH₄)₂SO₄

N = 15

H = 1

S = 32

O = 16

N × 2 = 30

H × 2 × 4 = 8

O × 4 = 64

30+8+32+64=134

Standard Hydrocarbons

Molecular Formulae	Hydrocarbon fuel
C H4	Methane
C2 H6	Propane
C3 H8	Ethane
C4 H10	Butane
C5 H12	Pentane
C6 H14	Hexane
C7 H16	Heptane
C8 H18	Octane
C9 H20	Notane
C10 H22	Decane

N.b. An Isomer is a compound with a standards molecular formulae with an unorthodox structural formulae.

For example:

Pentane

Dimethylpropane (neoPentane)

Formulae forms - As much as an A level student needs to know

Screenshot from Word Document: (Blogger was too awkward)

History of the periodic table - As much as an A level student needs to know.

• Aristotle: Theory of four elements, Fire, Water, Earth and Air. 330 BC




• Antoine Lavoisier: Wrote the first extensive list of elements containing 33 elements.



• Distinguished between metals and non-metals. 1770 - 1789



• Jons Berzelius: Developed a table of atomic weights. Introduced letters to symbolize elements. 1828



• Johann Dobereiner: Developed "Triads". Groups of 3 elements with similar properties. 1829



• John Newlands: Arranged the known elements in order of atomic weight, and proposed the Law of Octaves. 1864



• Lothar Meyer: Compiled a periodic table of 56 elements based on the periodictivity of properties such as molar volume, then arranged in order of atomic weight. 1869



• Demitri Mendeleev: Produced a table based on atomic weights, but arranged periodically with elements with similar properties under each other, and left gaps for elements not yet discovered. 1869



• William Ramsay: Discovered the Noble Gases. 1894

Reliability, Precision, Accuracy and Validity

	What is it?	How can it be applied in an experiment?
Reliability	Others can repeat your experiment and get the same reulsts.	This can be attained by repeating the experiment.
Precision	How small a measurement is.	This can be attained by using measuring instruments of a smaller scale, e.g. Vernier Calliper vs. Ruler.
Accuracy	How close a measurement is to the true value.	This can be attained by reducing all errors.
Validity	You can only make a conclusion if your measurement if your measurement have been affected by an independent variable.	This can be attained by carrying out a fair test.

Starter: Iron presence in the human body

Why is Iron present in the human body?

While one BlurIt user stated that Iron is needed in the human body for some reason to do with becoming an Iron man, another has given the reason to be directly related to the presence of haemoglobin which largely consists of Iron as a mineral and is quite important for the circulation of Oxygen throughout the body (As it seems that iron has an ability to enjoin the Dioxygen atoms).

How to test for Iron Deficiency (Anemia)?

Iron deficiency, known as Anemia, can be tested for via several methods, differing by the physical case, of which, the most prime is a complete blood test in which a blood sample is taken, and the amount of red cells in a certain volume is compared in ratio with the amount of white blood cells in the same volume, and then related to a default standard known to be “healthy beyond doubt”. This can also apply on other blood content, such as Transferrin proteins which are responsible of containing the iron in the haemoglobin. Other Anemia tests include, but are not limited to Ferritin tests examining the amount of iron in the body as a whole, Lead level test examinating lead toxicity which is a main cause of Anemia in children and Bilirubin tests examining if the red blood cells are being destroyed within the body which may be a sign of hemolytic anemia.

What is the relation between Titration and Anemia examinations?

Titration can also be used for the purpose of examining Anemia: You can find the concentration of iron(II) ions in solution by titrating with either potassium Manganate(VII) solution or potassium dichromate(VI) solution. The reactions are done in the presence of dilute sulphuric acid.

What is Titration and what are its uses?

Titration as I find it is a funny word, which refers to the chemical laboratorial process of examining the amount of reactant solution needed to complete a reaction with a second solution. This is most commonly known in the process of neutralisation, where a certain amount of Base can be added onto Acid until they are completely neutral (With the use of some nifty-coloured indicators!)

References:

http://www.chemguide.co.uk/inorganic/transition/iron.html

http://www.emedicinehealth.com/anemia/page5_em.htm

http://en.wikipedia.org/wiki/Titration