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Chemical Analysis of Salts: Anions and Cations

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Preliminary Test

Color of the Salt

Colourless

Absence of Cu 2+, Fe 2+, etc

Odour of the Salt

Ammoniacal smell

Vinegar smell

NH4

Acetate ion

Solubility

In water with no precipitate with Na2CO3

In dil HCl, soluble

NH4

No Group 1 cations

Salt is heated in a dry test tube

Colorless gas turns milky

Reddish brown fumes

Smell of ammonia

Pleasant smell

Carbonate

Nitrate ion

NH4

Acetate ion

Flame Test

Pale green

Brick red

Ba

Ca

Ash Test

Blue ash

Al


Systematic Analysis for Anions

Dil HCl is added to a little of the saltBrisk effervescence of a colorless gasCO3
Salt is rubbed with dil H2SO4 in a watch glassVinegar smellAcetate
Salt is heated with conc H2SO4Colorless pungent smelling gas is evolved and dense white fumes are produced when a glass rod dipped in NH4OH is shown near the mouth
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Fractional Distillation and Cracking Polymers: Separating Crude Oil

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To separate crude oil into its fractions, we use fractional distillation. This process occurs in an oil refinery. The crude oil is heated to about 350 degrees Celsius in a column that gets cooler higher up. Each fraction will evaporate and rise up the column until it reaches a part that is cool enough to condense it. The liquid goes into its respective tube and is separated from the rest of the crude oil. The smallest alkanes, which have a lower boiling point, will rise to the top. The largest fraction, bitumen, never evaporates and falls as a liquid to the bottom.

Cracking

Crude oil contains a mix of alkanes. Shorter alkanes are the most useful as fuels. We can obtain more shorter alkanes by breaking down the larger ones. This process is called... Continue reading "Fractional Distillation and Cracking Polymers: Separating Crude Oil" »

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Understanding Dental Materials: Properties and Clinical Significance

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Chemical Bonding in Dental Materials

Primary Bonds

Factors Influencing Material Properties:

  1. Type of bond between atoms and molecules
  2. Inter-atomic distance
  3. Atomic packing

Matter: Any substance that has mass and occupies space.

Atom: The fundamental unit of matter, consisting of a central nucleus (protons and neutrons) surrounded by electrons.

Types of Primary Bonds:
  • Ionic Bond: Attraction between positive and negative ions. Characteristics: Strong, heat resistant, insulator, insoluble in organic solvents, basic bond in ceramics.
  • Covalent Bond: Sharing of electrons between two atoms. Characteristics: Strong, insulator, water insoluble, basic bond in polymers.
  • Metallic Bond: Attraction between positive atomic cores and free electrons. Characteristics: High
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Coh3 chemical name

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in the RUTHERFORDS atomic model, the electrons are orbiting around the nucleous. In the nucleus are the neutrons and protons. BOHRS atomic model, the electrons move in stable orbits around the nucleus. Each orbit present a different number of electrons. How do we identify isotopes? By the name of the chemical element followed by its mass number. The elements in the periodic table are grouped: increasing atomic number(periods), similarity in physical and chemical elements(columns). Crystals are a gorup of atoms ordered ina geometric structure.
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Coh3 chemical name

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T     1.  A substance is matter that is always made up of The same combination of atoms.

F     2.  A mixture is matter that is made up of atoms of Two or more elements
Chemically bonded together.

F     3.  In a homogeneous mixture, substances are not Evenly mixed.

T     4.  In a mixture, the components keep their own Properties.

5.         In which way do mixtures differ from compounds?

C.  A mixture requires a physical change; a compound Requires a chemical one.

6.         Another name for a homogeneous mixture is

B.  A solution.

7.         A compound is the chemical bonding of

A.  Two or more elements.

8.         Which item is a mixture?

A.  air

9.         A sample of matter that contains

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Understanding States of Matter and Separation Techniques

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States of Matter

DIBUJO: 1 Liquid 2 Boiling point 3 Evaporating 4 Sublimation 5 Condensation 6 Melting 7 Solidification 8 Reverse sublimation

Evaporating

: It's not necessary to vaporize at 100°C

Boiling

: It's when a substance transforms to the gas state at a temperature of 100°C or higher

Graph

: 1-First, it's a solid substance 2 then the temperature increases 3 the solid substance melts and starts being a liquid substance 4 the temperature increases 5 the liquid substance vaporizes and starts being a gaseous substance 6 the temperature increases

Verify Pure Substance

: We know that a substance is pure because it has specific properties.

Sand+water

: Sedimentation - the sand stays at the bottom of the container and the water can be separated from... Continue reading "Understanding States of Matter and Separation Techniques" »

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Coh3 chemical name

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Chapter 1 : Matter and change

Branches of chemistry

Organic Chemistry – the study of most carbon-containing compounds.

Inorganic Chemistry – the study of most non-carbon-containing compounds.

Physical Chemistry – the study of the properties and changes of matter and their relation to energy.

Biochemistry – the study of substances and processes occurring in living things.

Analytical Chemistry – the identification of the components and composition of materials.

Theoretical chemistry – the use of mathematics and computers to understand the principles behind observed chemical behaviour and to design and predict the properties of new compounds.

Matter

Atom – the smallest unit of an element that maintains the chemical identity of that element.

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Understanding Mixtures, Phases, and Chemical Reactions

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Mixture

A mixture is a physical blend of two or more components.

Heterogeneous mixture

A mixture in which the composition is not uniform throughout is a heterogeneous mixture.

Homogeneous mixture

A homogeneous mixture is a mixture in which the composition is uniform throughout. Another name of homogeneous mixture is a solution.

Phase

The term phase is used to describe any part of a sample with a uniform composition and properties.

Filtration

The process that separates a solid from the liquid in a heterogeneous mixture is called filtration.

Distillation

One way to separate water from the other components in tap water is through a process called distillation.

Properties of Matter

Mass

The matter of an object is a measure of the amount of matter the object... Continue reading "Understanding Mixtures, Phases, and Chemical Reactions" »

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chem

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Acid: Proton donor. Produces Hydronium ions
  - Taste sour, tart, sharp & conduct electricity
  - Stringing sensation & react with metals 
  - Changes litmus paper blue to red
Base: Proton acceptor. Produces Hydroxide ions(OH)
  - Bitter taste & slippery feel
  - Dissolves in water & neutralize acid
  - Changes litmus paper red to blue
Conjugated acid: gain a proton.  
Conjugated base: loses a proton
Neutralization: acid & base react to produce salt & water
Strong electrolytes: strong acid, base 7 soluble salts
pH 7: Neutral      pH 8-14: base   pH 0-6: acid
Acid & neutral solution: colorless 
Basic solution: pink
Red litmus (acid):  in acid (red), in neutral (red), in basic (blue)
Blue litmus (acid): in acid (red)
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General Biology Test: Questions and Answers

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1- Explain the process of making monomers and polymers.

Monomers are small subunits that when bound together form polymers

Polymers are formed by either dehydration or by hydrolysis

2- Define Cytoskeleton with its characteristics.

Structural framework consist of protein tubules, filaments: Microtubules, Microfilaments, Intermediate filaments

3- What is another name for protein channel that link cells?

Adhesion proteins – permit cell to stick together

4- What are the characteristics of phospholipids

Each phospholipid contains head and tail (head is hydrophilic, means it is attracted to water; the tails is hydrophobic, repels water)

5- What is the primary component of a cell membrane made of?

Phospholipids (glycerol bond, 2 fatty acids, phosphate group)... Continue reading "General Biology Test: Questions and Answers" »

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