# Posts by Shane O'Brien

### Organic Chemistry – Summary

General Definitions Organic Chemistry is the study of compounds of Carbon. Hydrocarbons are carbons consisting of carbon and hydrogen only, bonded together covalently. They are used as fuel and feedstock for the chemical industry. Main Sources: Coal, Methane, Crude Oil. Structural isomers are compounds that have the same molecular formula but different structural formulas. Homologous Series is defined as: A series of compounds of… Continue Reading →

### All Physics Definitions for Leaving Certificate

Light Refraction is the bending of light as it goes from one medium to another. Laws of Refraction: (1) Incident ray, refracted ray & normal are on the same plane.  (2) Sine I/Sine R is constant. Refractive Index: Sine I/Sine R = 1/Sin C = Real depth/Apparent depth = c1/c2 Critical Angle: The… Continue Reading →

### Leaving Cert. Maths Construction Video Tutorials

Angle Bisector Perpendicular Bisector of Line Segment Perpendicular through point not on line Perpendicular through point on line Line parallel to given line through a point Division of segment into 2 or 3 equal parts Division into any number of parts Segment of given length, on given ray

### Axioms, Corollaries & Theorems

Axioms Axiom: A statement or proposition that is regarded as being established, accepted, or self-evidently true. Axiom 1: There is exactly one line through any two given points Axiom 2: [Ruler Axiom]: The properties of the distance between points. Axiom 3: Protractor Axiom (The properties of the degree measure of… Continue Reading →

### Theorems to Learn for Leaving Cert. HL

Theorem: A general proposition not self-evident but proved by a chain of reasoning; a truth established by means of accepted truths. 1. Vertically opposite angles are equal in measure. 2. In an isosceles triangle the angles opposite the equal sides are equal. Conversely, if two angles are equal, then the… Continue Reading →

### All Chemistry Definitions to Learn for Leaving Certificate

The Atom Dalton’s Atomic Theory: All matter is made up of indivisible atoms which cannot be created or destroyed. William Crookes discovered the Electron. Cathode ray tube. JJ Thomson determined that electrons were negative. Found E/M ratio. Robert Millikan’s Oil drop experiment discovered size of electron’s charge. Plum Pudding Model:… Continue Reading →

### The Windhover – Hopkins’ Poetry Notes

Summary The poem describes a falcon the poet  has observed. The poem describes how  majestic the falcon is. He compares it to  Jesus, in beauty, strength, bravery and  action. He sees Christ as a warrior. Themes God & Nature – The falcon inspires Hopkins to think of  God. It’s strength, bravery… Continue Reading →

### Short Quotes & Notes about Macbeth

Brave, Noble Soldier “Till he unseam’d him from his nave to his chaps” “Bellona’s bridegroom” “Noble macbeth” “Valour’s minion” Ambitious, but not ruthless “I have no spur to prick the sides of my intent, but only vaulting ambition” “I do fear thy nature, it is too full o’ the milk… Continue Reading →

### Oil Refining: Organic Chemistry – Summary

Fractional Distillation: This involves the heating of crude oil, and separating the various mixtures in the basis of their boiling points. Octane Number The Octane Number of a fuel is a measure of the tendency of the fuel to resist knocking. Heptane = 0 2,2,4 Trimethylpentane = 100 Shorter the alkane chain, higher the octane number. More… Continue Reading →

### Die Schule – Q & A for German oral exam

Some questions and answers about school life that may appear in your German oral exam. Wie kommen Sie zur Schule? Ich komme immer mit dem Bus zur Schule. Welche regeln gibt es hier? Die Schule ist sehr streng, und es gibt viel regeln. In der Mittagspause, dürfen wir nicht ins… Continue Reading →