Reactions of acids

Salts are mainly ionic compounds

Reactions of acids
1. Acid + metal -> Salt + Hydrogen gas
2. Acid + Carbonates -> Salt + Water + Carbon dioxide gas
3. Acid + base -> Salt + Water

1. Hydrochloric acid + Magnesium -> Magnesium + Hydrogen gas

Remember all the relevant polyatomic ions
- In notebook

Conductivity of Solutions
Yes
- Tap water
- Sodium chloride
- Salt water
- Hydrochloric acid
- Sodium hydroxide
- Vinegar
No
- Distilled water
- Sugar water
- Ethanol

Hydrochloric acid is found in stomach acid
Nitric acid is found in acid rain
Sulfuric acid is found in acid rain
Phosphoric acid is found in cola
Acetic acid / Ethanoic acid is found in vinegar

Basicity depends on how many hydrogen ions are released when one molecule of an acid molecule is dissolved in water

Strong acids completely dissociate in water
Weak acids partially dissociate in water

Acids and Bases, from class notes

I know I've already done a post about acids and bases. But we're doing it again in class, so yeah... I'm just kinda taking notes.
Acids:
1. Tastes sour
2. Turns blue litmus paper red
3. pH < 7
4. Contains/Produces hydrogen ions, Hydrogen ions must be present (H+)

Examples:
- Hydrochloric acid (Strong acids)
- Sulfuric acid (Strong acids)
- Nitric acids (Strong acids)
- Ethanoic acid (Weak acids)
- Carbonic acid (Weak acids)

They can be grouped according to their 'strength'. Like strong and weak acids.
The above chemical formulas for all these examples are in my notebook.. cause they can't be typed out.

You only see ions when the acid is in water, it needs to be in water.
Dissociation means that something has been broken up. Something can mean the above chemical formulas.

Hydrogen must always be a '+'.
graphite is a covalent compound that can conduct electricity (delocalized electrons)

Concept Map:)

By the way, i created a mind map/concept map about acids, bases and indicators and the link is here:
http://popplet.com/app/index.php#/437731

Indicators

Concentration
- How much a substance is dissolved in 1 dm3 of the solution
Strength
- How easily an acid/alkali dissociates when dissolved in water.

Universal Indicator
- Determines the pH value of a solution
- pH of a solution is derived based on number of hydrogen ions/hydroxide ions in a solution.
- Acids with smaller pH value have higher concentration of hydrogen ions
- Alkaline solutions with larger pH value have higher concentration of hydroxide ions.

pH of soil is important because the growth and development of plants is affected by this. Most plants grow the best when the soil is neutral or slightly acidic (pH 6 or 7).

Bases and Alkalis

Base is any metal oxide or hydroxide.
Base contains either oxide or hydroxide ions
Base can also be defined as a substance which reacts with acid to give a salt and water only.
General equation for this reaction:
base + acid -> salt + water

Alkalis are a special class of bases
Alkali is a use that is soluble in water.
E.g. sodium hydroxide
Properties:
- Bitter taste and soapy feel
- Turn red litmus paper blue
- All alkalis produce hydroxide ions when dissolved in water
- Alkalis can react with acids to form a salt and water only
   - Reaction called: Neutralisation
- Alkalis heated with ammonium salts give off ammonia gas.
General equation for this reaction:
alkali + ammonium salt -> ammonia + water + salt
- Alkalis react with a solution of one metal salt to give metal hydroxide and another metal salt.
General equation for this reaction:
alkali + salt (of Metal A) => metal + salt (of Metal B) hydroxide

Uses:
Ammonia solution
- Window cleaning solution
- Fertilisers
Calcium oxide
- Neutralising acidic soil
- Make iron, concrete and cement
Sodium hydroxide
- Soaps and detergents
- Industrial-cleaning detergents
Magnesium hydroxide
- Neutralise acid on teeth (Toothpaste)
- Relieve indigestion (antacids)

Acids

Acid is a substance which produces hydrogen ions, H+, when it is dissolved in water.
All acids contain hydrogen but not all compounds that contain hydrogen are acids. It is the hydrogen ions produced that are responsible for the properties of acids.

Properties:
- Sour taste

- Dissolve in water to form solutions which conduct electricity

- Turn blue litmus paper red

- React with reactive metals to form hydrogen and a salt.
General equation for this reaction:
metal + acid -> salt + hydrogen

- React with carbonates to form a salt, carbon dioxide and water
General equation for this reaction:
carbonate + acid -> salt + water + carbon dioxide

- React with metal oxides and hydroxides to form a salt and water only
General equation for reaction of acid with metal oxide:
metal oxide + acid -> salt + water
General equation for reaction of acid with metal hydroxide:
metal hydroxide + acid -> salt + water

Acids show the properties of acids when they are dissolved in water. Acids dissociate in water to produce hydrogen ions which show the acidic properties.

Uses:
Sulphuric acid:
- Detergents
- Fertilisers
- Car batteries
Ethanoic acid:
- Preserve food (vinegar)
- Adhesives (glue)
Hydrochloric acid:
- Leather processing
- Cleaning metals

Chemical Bonding
- Formation of ions
- Formation of ionic bonds & covalent bonds
- Properties of ionic & covalent compounds
- Structure of simple, molecular & giant molecular structures

Noble Gas Structure
- Eg. He, Ne, Ar, Kr, Xe
- Each atom has 8 valence electrons (except for He)
- Single atoms
- Do not form compounds
- Described as unreactive
- Stable due to fully filled outer shells

The Octet Rule
- All atoms without a fully filled outer shell is unstable
- Unstable atom would try to gain stability by surrounding itself with an octet (8) of electrons
- Octet Rule

Helium (He)
- 2 outer electrons
- Stable atom because outer shell is fully filled
- Duplet Rule

Valency
- Number of electrons needed to fill up the outer shell
- Number of electrons in excess to the atom, stopping the atom from having a fully filled outer shell

Formation of Ions
- Charged particle formed from an atom/group of atoms by the loss/gain of electrons
- Metals formed positively charged ions called Cations.
- Non-metals formed negatively charged ions called Anions.

Formation of Positive Ions
- Formed by loss of electrons
- Metals tend to form positive ions because most metal atoms have less than 4 electrons in the outer shell. Hence it is more likely to lose the few electrons than to gain many more to achieve octet structure.

Formation of Negative Ions
- Formed by the gain of electrons
- Non-metals tend to form negative ions because most non-metals have more than 4 electrons in the outer shell. Hence, it is more likely for the atoms to gain a few more electrons to complete the octet than to transfer their outer electrons to other atoms.

Ions
- Positive and negative ions can be formed by a group of atoms, known as polyatomic ions

Ionic Bonds
- Formed between metals and non-metals
- Involves the formation of both positively charged ions (cations) and negatively charged ions (anions)
- Involves the transfer of electrons from one atom to another
- All metal atoms are known as electron donors and all non-metal atoms are known as electron receivers.

Ionic Compounds
- Made up of oppositely charged ions, NOT molecules
- Oppositely charged ions are arranged together in a giant ionic structure
- Lattice structure/Crystal lattice
- THree-dimensional network of atoms/ions which are packed together in a regular pattern
- Held together very tightly because oppositely charged ions attract one another strongly
- High melting and boiling points
- In order for the ionic solid to melt, a very large amount of heat energy is needed to break up the strong ionic bonds
- All ionic compounds are solids at room temperature
- Substances with low melting and boiling points are known as volatile
- Ionic compounds - Non-volatile
- Solubility:
       - Most ionic compounds can dissolve in water
       - Water molecules can separate the positive ions from the negative ions
       - Ionic compounds do not dissolve in organic solvents
- Able to conduct electricity in the molten (liquid) state) and as an aqueous solution
- Moving ions acts as charges carriers to conduct electricity

Covalent Bonds
- Two non-metals reacting with each other
- Bond formed by the sharing of electrons is called Covalent Bond
- In the case of ionic bonding, atoms would achieve stable duplet/octet structure by donating or receiving electrons. All non-metal atoms have a choice of whether to undergo ionic or covalent bonding depending on the nature of the other reactants.

Molecules of Compounds
-

Atomic Structure

Atoms are made up of three different particles - protons, neutrons and electrons. They are called sub-atomic particles.
Protons and neutrons are tightly packed together in the centre of an atom, forming the nucleus of the atom. Protons and neutrons are known as nucleons.
An atom contains an equal number of positively charged protons and negatively charged electrons.
Proton number
- Also known as atomic number
- Represented by the symbol Z
- Different atoms have different numbers of protons

Nucleon number
- Total number of protons and neutrons in an atom
- Represented by the letter A
- Also known as mass number
Nucleon number (A) = number of protons + number of neutrons

Isotopes
- Atoms of the same element with the same number of protons but different number of neutrons
- Same chemical properties but slightly different physical properties
- Emit high energy radiation called radioisotopes

Electrons
- Move around the nucleus in regions known as electron shells
- The way the electrons are arranged in an atom is also known as the atoms' electron structure or electronic configuration

Valence Electrons
- The shell that is furthest from the nucleus
- Also known as outer shell
- Chemical properties of an element depend on the number of valence electrons

Kinetic Particle Theory and Changes of State

Changes of state are reversible.
Substances change state because:
- When the matter is heated/cooled, the heat absorbed/given out causes the kinetic energy of the particles to change. Thus, the substance changes its state

Melting
Substance changes from solid to liquid.
Temperature which solid becomes a liquid is called melting point.
Graph is known as the heating curve
Heating curve shows how the temperature of a solid changes as it is heated to the melting point.


Freezing
Substance changes from liquid to solid
Temperature which liquid becomes a solid is called freezing point.
Graph is known as cooling curve.
Cooling curve shows how the temperature of a liquid changes as it is cooled to the freezing point.


Boiling
Substance changes from a liquid to gas
Temperature which liquid boils to become a gas is called boiling point.
- Bubbles of gas are seen when a liquid boils.

Evaporation
Liquid turns into a gas at temperatures lower than the boiling point
Particles have enough energy to escape as a gas from the surface of the liquid
Liquids that evaporate quickly at room temperature are called volatile liquids.
Example: Perfume and petrol

Similarity between Evaporation and Boiling:
Involves a liquid changing into a gas

Differences between Evaporation and Boiling:

Boiling	Evaporation
Occurs only at boiling point	Occurs at temperatures below boiling point
Occurs throughout the liquid	Occurs only at the surface of the liqiuid
Occurs rapidly	Occurs slowly

Condensation
Gas is cooled sufficiently and changes into a liquid
Water vapor touches a cold surface, condensation occurs and water droplets are obtained

Sublimation
Solid change directly into a gas.
Particles at the surface of the solid have enough energy to break away from the solid and escape as gas.
Examples: Iodine and Ammonium chloride
Substances that sublime might change directly from a gas into a solid without going through the liquid state.
- Keeps things cool

Kinetic Particle Theory and The Three States

All matter is made up of tiny particles and these particles are in constant, random motion.
Moving particles have kinetic energy, thus the name kinetic particle theory.

Kinetic Particle Theory
- Describes the states of matter
- Explains differences in properties of solids, liquids and gases
- Explains the changes of state

Solid state
Fixed shape:
- Closely packed in an orderly pattern
- Held together by very strong forces of attraction
- Cannot move about freely
Fixed volume:
- Cannot be compressed since the particles are very close to each other

Liquid state
- Particles have more kinetic energy than particles of the same substance in the solid state
No Fixed Shape:
- Forces of attraction between particles are weaker than in a solid
- Not held in fixed positions
- Arranged in a disorderly manner
- Can move freely
Fixed volume
- Particles are farther away from one another than in the solid
- Particles are still packed quite closely together
- Cannot be compressed

Gaseous state
No Fixed Shape:
- Particles are spread far apart
- Forces of attraction are very weak
No Fixed Volume:
- Particles have a lot of kinetic energy
- Particles are not held in a fixed position
- Particles have a lot more space between each other, thus they can be compressed

Lesson Notes

Crystallization

1.       Making a substance pure

2.      Solution should be saturated

3.       Change of state of substance from aqueous (aq) to solid.  (Solution was dissolved in water)

Chromatography

1.     To separate a mixture

2.    Find out number of components

3.     Depends on solubility of compounds or substances in a solvent

Green ink is less soluble thus it would choose to stay on the chalk and won’t move up as quickly

Red ink is more soluble thus it would move up with the water up the chalk

Filtration

1. Differentiate between differently-sized substances

How to separate Mixtures

For the HBL assignment, we basically learnt how to separate Mixtures. I'll post more info later:)
Fractional distillation!
Basically, our group did fractional distillation:)

Reflections on what I've learnt so far:)

Basically I think I really enjoy Chemistry:) Yay:) But I'm not sure if the feeling will change as we go deeper into the topic. But as of now, I like it:)

I guess learning about the elements and stuff was interesting, mainly because it's new... To be frank, I've never really heard of a periodic table until we started Chemistry and I think although the table looks scary, it's actually quite cool. I think it's cool how so many elements can be organized in such a neat table which everyone can understand.
I would say trying to understand the stuff about the three or two main groups of elements was slightly easier since we did something similar in primary school. It was probably the part that we just did today (trying to group the page of "letters" into three or four different groups. I had a few wrong, I think I understand but I'll try again to see whether I really understand before I make some clarifications. I thought the molecules, atoms, elements, compounds and mixtures thing was a little bit confusing but let's see how things go:)

Alloys

Alloys are an example of a mixture. An alloy is a mixture of metals with other elements.Alloys are used more frequently than metals because they are stronger.

Mixtures

Mixtures are formed when two substances are added together without chemical bonds being formed.
Examples: muddy water and air

Mixtures can be made up of elements and compounds.

Compounds

A compound is a pure substance that contains two or more elements chemically combined.
The compound that contains two or more elements ends with an -ide.
magnesium + oxygen -> magnesium oxide

When the elements are chemically combined, there is always a fixed ratio.
Example: the ratio to hydrogen atoms to oxygen atoms in water is always 2 :1.

The smallest part of a compound is a molecule. Depending on the compound, the smallest particle can also be called the formula unit.
A compound can be represented by a chemical formula.


Heat can be used to form compounds. Heat can also be used to break down compounds into elements or simpler compounds. Electricity can also be used to break down compounds.

Iodine

1. Metallic, non-metallic or metalloid?
Ans: Non-metallic

2. Appearance
Solid: Bluish-black. Vapor: Purple

3. Physical properties
Boiling point: 184 degrees celsius
Melting point: 113.5 degrees celsius
Conductor of electricity: Poor conductor of electricity
Conductor of heat: Poor conductor of heat
Hardness/brittle/malleable/ductile: Not too sure, malleable?

4. Uses and occurrence
Iodine is needed by our body for metabolism in our cells. Iodine is also required for the thyroid glands to function normally.

Sources:
http://www.chemicool.com/elements/iodine.html
http://www.livestrong.com/article/501359-characteristics-of-iodine/

Elements

Notes I picked out:
Different elements are represented by different chemical symbols
Elements are pure substances that cannot be broken down into two or more simpler substances by chemical processes or electricity.
Examples: copper
Water is not an element because it can broken down by electricity into hydrogen and oxygen.

Elements can be classified into two major groups: Metal and Non-metal
Metals exist as atoms in a giant structure and most non-metals exist as molecules
Elements that have both properties of metals and non-metals are called metalloids.
Example: silicon

Elements are made up of tiny particles called atoms.
Elements that do not exist as atoms are called monatomic elements. Their atoms are not joined together chemically.
A molecule is a group of two or more atoms that are chemically combined. The molecular formula of an element is the chemical symbols plus the number of atoms needed when a molecule of that element is formed.
Molecules formed by the combination of two atoms are called diatomic molecules. Molecules that consist of three atoms are called triatomic molecules. Molecules that are formed by four or more aims are called polyatomic molecules.

Hello:)

Hi everyone, I'm Renne:) This blog if for blogging stuff about Chemistry!