## Polymerization is simply the process of putting together monomers (single molecules), to become a long chain of molecules (called polymers) with the use of a catalyst.

Polymerization is an important process for making plastics.

## A catalyst

A catalyst is a substance that increases the rate of a chemical reaction without itself undergoing any permanent chemical change.… Read the rest

## How to calculate the number of moles

Question: How many moles are in 1000 g of sucrose?

## 1. Obtain the atomic mass

First, write down the formula for sucrose: C12H22O11

## 2. Calculate the molar mass of sucrose C12H22O11

The formula tells us there are 12 carbon atoms, 22 hydrogen atoms, and 11 oxygen atoms.… Read the rest

## Molar Mass

Molar mass is the weight in grams of one mole of a chemical substance.

## How to calculate the molar mass of a single element (eg.hydrogen)?

The molar mass for an element is the sum of atomic masses, expressed as g/mol.

Molar mass of hydrogen = 1.008 g/mol

## The mole is used in measurements in a way similar to the use of “dozens”.

• The reason why we use moles in chemistry is because of the vast number of molecules and atoms involved in the calculations
• Just like it’s easier to manage the thought of 2 dozen eggs instead of 24, scientists prefer to think of a reaction requiring 2 moles of carbon rather than 1,204,428,200,000,000,000,000,000 particles
• The number is huge and unimaginable, a bit like the number of stars in the galaxy
• Using the mole unit helps simplify calculations

Note: the symbol for mole is “mol”

## Sublimation

Sublimation is the process of turning from solid to vapor without going through the intermediate liquid phase.

## Sublimation of Ice

We are all familiar with ice melting before it evaporates. However, in sublimation, the liquid phase is omitted. In order for a solid to sublime, it must exhibit a higher than usual vapor pressure and weak intermolecular attractions.… Read the rest

## Dissociation is the breaking down of a compound into elements

The word dissociate and disassociate have similar meaning – to remove from being connected.
When a compound dissociates, the bonds are broken.

## Ionic compound dissociation

All ionic compounds dissociate to some extent when they dissolve in water.… Read the rest

## Osmosis

In 1784, a French physicist and clergyman named Jean Antoine Nollet made an interesting discovery. He filled a pig’s bladder with a concentrated solution of alcohol. He then put the bladder in water and the bladder expanded!

This interesting process is caused by a phenomenon called osmosis.Read the rest

## Properties of Colloids

Do you know that the cloudy water syndrome in a fish tank is caused by colloids? Over a period of time, organic waste produced by the fish and algae in the tank are turned into nitrates. These particles are interspersed in the water and do not settle.… Read the rest

## Brownian Motion

Irregular motion of suspended particles is called “Brownian motion”.
Watch an interesting Youtube video on the discovery of Brownian Motion by British botanist Robert Brown

## Robert Brown was a Scottish botanist who first discovered the Brownian motion.

He noticed random motion of pollen grains dispersed in water under a microscope as though they are constantly dancing.… Read the rest

## Atmospheric Pressure & Boiling Point

Water always evaporates no matter what the temperature or atmospheric pressure is.

Even in the coldest of winter, snow and ice can evaporate by a process called sublimation. They can turn straight into vapor (the gaseous stage) without melting.

The vapor that escaped into the air whether by evaporation or sublimation had sufficient energy to break away from the intermolecular forces of the water.… Read the rest

## Molality

Molality is defined as the number of moles of solute per 1 (kg) of solvent.

• Solute = particles you dissolve
• Solvent = the liquid you use for dissolving the particles

## Example

Calculate molality (m) of 29.8 g of glucose (C6H12O6) dissolved in 622.8 g of water

Symbol Element Atomic weight Atoms
C Carbon 12.01 6
H Hydrogen 1.008 12
O Oxygen 16.00 6

## Freezing Point Depression

Freezing point depression is simply the process of LOWERING THE FREEZING POINT OF A LIQUID by adding a solute to it.

Ordinarily, water freezes at 32°F (0°C), but can you add salt to lower its freezing point to 20°F (-6°C). That’s why we use salt to melt ice on the road in the winter!… Read the rest

## Boiling Point Elevation

Boiling point elevation is the elevation of a solid’s normal boiling point by adding a substance to it.

When you add a solute (such as salt or sugar) to a pure solvent (such as water), the boiling point of the liquid solvent is now increased.… Read the rest

## Vapor Pressure Lowering

Adding a solute to a pure solvent lowers the solvent’s vapor pressure. For example, water normally boils at 100ºC (212ºF) but if you add a substance like salt to the solution, it decreases the vapor pressure of the solution.

First, recall what the vapor pressure of a liquid is.… Read the rest

## Colligative Properties of Solutions

The characteristics of a solution such as the boiling point, freezing point and vapor pressure are known as colligative properties. Colligative properties apply only to solutions and not gases or solids.

## COLLIGATIVE PROPERTIES ARE DEPENDENT ON THE NUMBER OF ATOMS AND MOLECULES

The word colligative comes from the same Latin root that the word collection comes from.… Read the rest

## Nonpolar molecules do not dissolve readily in water

• Nonpolar molecules do not become hydrated – they are repelled by water
• The molecules are insoluble or almost insoluble in water

Oils and fats are examples of hydrophobic substances. For example, if you mix oil with water, the mixture will separate.… Read the rest

## A nonpolar covalent bond is a chemical bond where electrons are shared equally between two atoms

The electrons are shared equally between the two atoms

## Nonpolar covalent bond electronegativity scale

If the difference in electronegativity between two atoms is 0.4 or less, the bond formed between the two atoms is a nonpolar covalent bond.… Read the rest

## The electrons are unequally shared between two atoms

When a chemical bond involves “the sharing of a pair of electrons by two atoms in a molecule”, it is generally called a covalent bond.

In a polar covalent bond, the electrons are not equally shared between the atoms

## Dipole moment

The unequal sharing of electrons causes a separation of partial charges within the bond.… Read the rest

## An ionic bond

An ionic bond is formed between elements of large differences in electronegativities, which are typically found between metals and non-metals.

The atom that loses the electron(s) becomes a positively charged ion called a cation, and the one that gains the electron(s) is called the anion.Read the rest

## HOW DO YOU FIND OUT THE TYPE OF BOND

If you’re given two elements, such as carbon and oxygen, how do you tell what type of bond they will form?… Read the rest

## Solubility

The solubility of a substance is the amount of that substance that will dissolve in a given amount of solvent.

## The difference between solute and solvent

• SOLUTE – the substance to be dissolved
• SOLVENT – the liquid for dissolving the substance

## Fizzy drinks

Fizzy drinks are made by dissolving carbon dioxide gas in water.… Read the rest

## Definition, Obits and Energy Level

Definition

The valence electrons are the electrons in the outermost shell or last energy level of an atom.

valence electrons are electrons in the last shell of an atom

Valence electrons are electrons in the highest principal energy level.

They are electrons that sit in the outermost shell of an atom.Read the rest

## ELECTRONEGATIVITY

Electronegativity is a measure of how strongly an atom – in a molecule – is able to attract electrons in a bond to itself.

Factors affecting electronegativity:

## 1) The atomic number

The atomic number is the number of protons in the nucleus of an atom.… Read the rest

## Hello and welcome to Sufguppy.

Surfguppy provides free online chemistry notes for high school and college students. If you’re a teacher or student, please feel free to use our materials for non-commercial purposes. A small portion of materials on this website belongs to Creative Commons, please check the Creative Commons Licensing Terms to use them.… Read the rest

## Why is water polar?

Why is water polar and why is the water molecule a bent shape?

Water is polar because it has one end that is slightly negatively charged, and another end that is positively charged.

The water molecule is made of one oxygen atom and two hydrogen atoms.… Read the rest

## The Bohr Model

In 1913 Niels Bohr proposed a model to describe how energy levels are organized around an atom. While his model is now known to be incorrect, it is useful for understanding energy levels as Bohr’s model closely resembles planets orbiting the sun (a visual that we are familiar with).… Read the rest

## Ionization Energy Trend

Ionization energy is defined as the amount of energy needed to eject a valence electron from an atom in the gas phase. It is measured in kJ/mol.

A valence electron is simply an electron located in the outermost energy level of an atom.… Read the rest

## Periodic Table Trends

Today, we are going to learn about how the periodic table is organized and the important information that it provides.

Scientists discovered that if they arranged the elements according to their atomic number, properties of the elements would occur in a regular and repeating pattern.… Read the rest

## Electronegativity Bond Scale

`Photograph of Linus Pauling: Nobel Foundation, Public domain, via Wikimedia Commons`

The above is an example of electronegativity bond scale. It shows the different types of chemical bonds formed between atoms based on the electronegativity difference.

Bond scale varies slightly from textbook to textbook but the Pauling scale is the most commonly used.… Read the rest

## The Mole Relationship to Carbon

Experiments have determined that in 12 g of carbon there are 6.02 x 10²³ atoms.

1 mole is defined as the number of atoms in 12 g of carbon.

In other words, 1 mole of carbon contains 6.02 x 10²³ atoms!… Read the rest

## Carbon-carbon bonds

A carbon atom has 4 valence electrons

## A single bond

Most bonds that carbon form are single bonds. Single bond simply means sharing one pair of bonding electrons between two atoms and is represented by a single line.

Two carbon atoms forming a single bond

In ethane, two carbons atoms share a single bond

## A double bond

A carbon atom can also form multiple bonds with other carbon atoms.… Read the rest

## 1 mole = 6.02 x 10²³ particles

A mole of any substance contains a fixed and very large number of particles, known as Avogadro’s constant. Avogadro’s constant is approximately equal to 6.02 x 1023 particles, which can be tiny particles such as atoms or molecules.… Read the rest

## What is a COVALENT BOND?

The term covalent bond is used to describe the bonds in compounds that result from the sharing of one or more pairs of electrons.

• There are two types of covalent bonds – nonpolar and polar covalent bonds
• In nonpolar covalent bonds, the electrons are shared equally between the two atoms
• In polar covalent bonds, the electrons are are not shared equally and will be closer to the atom with the higher electronegativity
• Please note: The electrons are shared, not transferred so there is no loss or gain of electrons

## How to calculate molecular mass?

1. Determine the formula of the compound
2. Use the periodic table, determine the atomic mass of each element present in the formula
3. Multiply the atomic mass of each element by the number of atoms
4. Finally, add the atomic masses

## 3 Simple Steps – the Ring Structure of Glucose Molecule

For drawing purposes, the ring structure of the glucose molecule is broken down into three simple steps as shown below.

Each molecule of glucose sugar is only 1 unit consisting of 6 carbon atoms, 12 hydrogen atoms and 6 oxygen atoms in the form of a ring or a straight chain.Read the rest

## Simple Sugars – Monosaccharides

What are Monosaccharides?

Monosaccharides are known as simple sugars, they are the simplest form of carbohydrate. They are short chain molecules containing only one chemical ring. Since they are only one ring, they can undergo chemical reactions to provide quick release of energy.… Read the rest

## Organic Chemistry

Carbohydrate chemistry is a branch of organic chemistry that studies carbon compounds. Carbon can be found in food and non-food substance. As carbon plays a huge role in living things, organic chemistry is very important to medicine and life science.… Read the rest

## Glucose C6H12O6

• Glucose is a carbohydrate and it is one of the smallest units of sugar
• Its chemical formula is C6H12O6
• Glucose are hexoses – 6 carbon atoms sugars
• In total, there are 24 atoms that form the molecule

## Step 1:

Draw 6 carbon molecules and draw arms except for the first one

## Step 2:

Draw 5 hydrogen to carbon bonds
(4 on one side and 1 on the other)

## Step 3:

Fill remaining spaces with ( OH ) group.

## Open, Closed & Isolated Systems

A system refers to any parts of the universe being studied.

If you are conducting an experiment in a beaker, then the system you are studying is in the beaker.

The system is subject to surrounding factors such as air temperature and pressure.… Read the rest

## What is the Octet Rule of Electron Configuration?

Electron configuration is the arrangement of electrons in each energy level or shell of an atom.

• If the outer shell of an atom is not filled to its maximum level, the atom is still reactive and has a tendency to combine with other elements
• The atom only becomes stable when it is filled to the maximum level it can hold in the outer shell
• The octet rule is a rule of thumb that works most of the time with some exceptions

## Chlorine and fluorine fulfilling the octet rule

Fluorine has 7 valence electrons

Chlorine has 7 valence electrons

Chlorine and fluorine are bonded by sharing 1 electron each

Together they become a stable compound

Each atom now has 8 valence electrons (instead of 7) occupying its valence shell

## Enthalpy Change Calculation

Propane Combustion

When 0.5 g of propane is burned, the heat produced is used to raise the temperature of 100 cm³ of water from 20ºC to 40ºC. Calculate the enthalpy change (ΔH) for the reaction. Given the density of water is 1 g/cm³ and specific heat capacity of water is 4.18 kJ/(kg•C).… Read the rest

## Enthalpy, Entropy & Gibbs Free Energy

 Enthalpy Entropy Gibbs Free Energy Enthalpy is the amount of heat energy transferred (heat absorbed or emitted) in a chemical process under constant pressure. Entropy measures the amount of heat dispersed or transferred during a chemical process. Gibbs Energy is also known as energy available to initiate a chemical process and is determined under constant pressure and temperature.

## Enthalpy

The term enthalpy change is a term to describe the amount of heat that passes in or out of a system during a chemical reaction or a physical process.

• You: How much energy is absorbed when the ice melts in the cup?

## Reaction Spontaneity

(Picture above – dog escaping over the fence – winter 2015)

## A spontaneous process

A spontaneous process is a physical or chemical change that occurs with no outside intervention.

In life, many things happen spontaneously. For example, my dog escaped over the fence in the winter.… Read the rest

## Hess’s Law

Hess’s law states that energy change in the overall chemical reaction is the sum of energy change or enthalpy change in the individual reactions that comprises it.

• Hess’s Law states that the heat evolved or absorbed in a chemical process is the same whether the process takes place in one or in several steps.

## Methane gas – CH₄

What is the enthalpy change when methane is formed using carbon graphite and hydrogen?

When a chemical reaction takes place, heat is either given off or absorbed.

• If heat is given off, it is called an exothermic reaction.

## What is Gibbs Free Energy?

For a simple definition, Gibbs free energy can be described as the amount of energy available to do work.
 Gibbs Free Energy is invented by Josiah Willard Gibbs (February 11, 1839 – April 28, 1903) – an American scientist who made important theoretical contributions to physics, chemistry, and mathematics.

## Gibb’s Free Energy – Ammonia

The Haber process to manufacture ammonia using nitrogen and hydrogen is given by the equation below:

Calculate Gibb’s free energy change (ΔG) at 298 K temperature.
Given the entropy change (ΔS): -198 J K⁻¹ mol⁻¹
Enthalpy change (ΔH): -92 kJ

The Haber Process is a process of manufacturing ammonia in a factory.… Read the rest

## Entropy

What is entropy? Entropy refers to the amount of unusable energy in a system.
• When water flows over a dam, it loses some of its useful energy as heat
• Solid wood burns to become ash and releases gases.
• Solid ice melts to form liquid water.

## Carbon to Carbon – Single, Double & Triple Bonds

We know from the periodic table that a carbon atom has 4 valence electrons in the outermost shell.

In order for the atom to be more stable, the outermost shell must be filled up.

Carbon follows the octet rule of electron configuration.… Read the rest

## Condensation Polymerization

Condensation polymers are any kind of polymers formed through a condensation reaction where molecules join together–losing small molecules as by-products such as water or methanol.

en.wikipedia.org/wiki/Condensation_polymer

## Example – converting ethylene terephthalate to polyethylene

Step 1: Draw two different monomer molecular structure
MOLECULE A AND MOLECULE B

This pretty symbol you see is called an ester linkage formed by combining acid and an alcohol.… Read the rest

In addition polymerization, all the original atoms present used for making the polymers are retained in the end product.

## How to convert monomers to polymers?

Imagine you have a polymer called Ethylene.

Ethylene is a single molecule with the formula CH2H4.… Read the rest

## CLASSIFYING PLASTICS FOR RECYCLING

Plastic classifications is a system established to allow consumers to properly recycle and dispose of different types of plastics. Manufactures follow a coding system and place an SPI code on each plastic product, and are usually printed or modeled into the bottom.… Read the rest