Monthly Archives: October 2015

Six different types of reactions

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There are 6 different types of reactions: Synthesis, Decomposition, Single Replacement, Double Replacement, Neutralization, and Combustion. Each with a different meaning. So here is the six different types of reactions with their own little description.

Synthesis
A synthesis reaction or also known as a direct combination reaction is one of the most common types of chemical reactions. A synthesis reaction consists of two or more chemical elements to combine and create a more complex chemical form.
A + B = AB or 2K(s) + Cl2(g) → 2KCl(s
http://chemistry.about.com/od/chemicalreactions/a/synthesis-reaction.htm

Decomposition
A decomposition reaction or analysis reaction is when a chemical compound is broken into two or more smaller and simpler chemical elements.
AB = A + B or 2 H2O → 2 H2 + O2
http://chemistry.about.com/od/chemicalreactions/a/chemical-decomposition-reaction.htm

Single Replacement
A single replacement or substitution reaction is formed of one lone element and a chemical compound of two elements. The reaction happens when the unpaired element switches spots with one of the elements in the chemical compound.
A + BC = B + AC or Zn + 2 HCl → ZnCl2 + H2
http://chemistry.about.com/od/chemicalreactions/a/single-displacement-reaction.htm

Double Replacement
A double replacement or metathesis reaction consists of two chemical compounds formed of two elements. The reaction is created when one of the elements of each compound switched places to form two completely different compounds.
AB + CD = AD + CB or NaCl(aq) + AgNO3(aq) → NaNO3(aq) + AgCl(s)
http://chemistry.about.com/od/chemicalreactions/a/reactiontypes.htm

Neutralization
Neutralization or also known as water forming reaction is when an acid and base react to produce water and salt.
Acid + Base = Salt + Water or HCl(aq) + NaOH(aq) –> NaCl(aq) + H2O(l)
http://www.academickids.com/encyclopedia/index.php/Neutralisation

Combustion
A combustion reaction produces either light or heat, the most common reaction is fire. The majority of forms of combustion happen when the gas oxygen joins with another substance. For example, when wood burns, oxygen in the air joins with carbon in the wood. Combustion happens when when the substance reaches a temperature called ignition point. At this point, oxygen combines with the substance fast enough to create a flame (ex/ is when producing fire).
http://kids.britannica.com/elementary/article-399410/combustion

Henry Cavendish Experiment

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Discussion Questions:

List 3 safety precautions taken in this lab.

To wear safety goggles at ALL TIMES during the lab. If you have long hair to tie it back. Do not throw the burning pieces of wood in the garbage until you have dipped it in water.

What changes did you observe in your reactants? I.e. what were some observations of new products?

When the acid and mossy zinc were added together it started fizzing. The water kept fizzing during the whole experiment and changed into a light grey colour. When the zince and acid strated fizzing it would create hydrogen gas, which would be captured into the test tube. Once it was in the test tube we took a lit wood splint and help in over top of the hydrogen gas. once the fire and gas touched it made a ‘pop’ sound and for the splitest second the gas turned a orange colour.

a. How did the temperature change?

The tempertaure of the flask became hotter due to the fact that it was creating hydrogen gas. When the hydrogen gas was transfered into the test tube then the test tiube also became hot. Also I found that the test tube was the most hot after it created the little ‘pop’. It could have been hotter because when the hydrogen gas (being already hot) and the fire (being very hot) created the ‘pop’ the heat could have mixed together and created even more heat.

Look up the definitions, was the lab endothermic or exothermic? Explain your reasoning.

It is an exothermic lab because exothermic means that heat is being produed from the reaction (Exo= to exit, Therm= heat) . In the lab we putt zinc and acid together to create hydrogen gas, which was hot. The heat from the lab was beaing released, therefore meaning it is an exothermic lab.

Write out the formula for the chemical equation and balance it.
Zinc + hydrochloric acid produces Hydrogen gas + zinc chloride

Zn + HCl 》 H + ZnCl
[ ] Zn + [2] HCl 》 [ ] H + [ ] ZnCl

Look up Synthesis, Decomposition, Single Replacement, and Double Replacement Reactions. What type of reaction is this? Explain.

It is a single replacement reaction. In a single replacement reaction an element reacts with a compound and takes the place of an element within that compound. In a single replacement reaction a metal switches places with a metal and a non-metal switches with a non-metal. In this case as you can see { Zn + HCl = H + ZnCl } that Zinc and Hydrogen switched spots. In a single replacement reaction the elements switch when there is a better (more reactive) element nearby to switch with.

How did the change in surface area of the zinc affect the reaction rate? Which reacted faster?

I believe that the larger surface area would react faster because the solid-phase reactant increases the number of collisions per second and therefore increases the reaction rate.

How did the change in the concentration of HCl affect the reaction rate? Which reacted faster (1 M or 3M)?

3m would react faster because of the collision rate. If you had a beaker of 3m and 1m of HCl and dropped zinc in each one, the one with 3m would react faster because the zinc would come in contact with it first.

Ionic vs. Covalent Coumpounds

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Though they both contain atoms, ionic compounds and covalent compounds have lots of different differences.

FACTS:

Ionic Compound:
Ionic Compound is a metal + non-metal formula.
Ionic Compound atoms give electrons in order to become stable. Which is the reasonwhy they are electrically charged.

Covalent Compond:
Covalent Cmpound is a non-metal + non-metal formula.
Covalent Compound atoms share electrons in order to become stable. They are not electrically charged.

BOHR MODEL:

Ionic Compound:
Each atom is surrounded by a box within the box it shows it’s protons, neutrons and all electrons. There is a charge outside the top right corner of the box. The atoms are seperated in their own drawing, none of it is connecting.
Ionic compound bohr diagram

Covalent Compound:
The atoms are all attached, to show how the atoms share the electrons. The protons, neutrons and electrons are all shown in the atom. There is no box or charge.
Covalent compound bohr diagram

LEWIS MODEL:

Ionic Compound:
The atoms are once again surrounded by a box with the charge at the top right corner. The atom only shows the symbol in the middle with the valence electrons on the outside.
Ionic compound lewis diagram

Covalent Compound:
The atoms have a line connecting the non-metals together on the sides where they are sharing electrons. Where there is no connecting parter, the outer electrons are shown. The atom only shows the symbol in the middle with the valence electrons on the outside (depending if it is connecting and sharing electrons with a different atom).
Covalent compound lewis diagram

NAMES:

Ionic Compound:
Ionic Compounds have no prefixes, the last atom always ends with “ide” unless it is a polyatomic ions.

Covalent Compound:
Covalent Compounds use prefixes for all atoms (ex/ mono, di, tri, tetra…). All ending atoms end with “ide” unless it is a polyatomic ion.

FORMULA:

Ionic Compound:
Formula’s for Ionic and Covalent both resemble the same for look wise. In order to figure out how many atoms you need, you will need to perform an equation.
Ex/ Aluminum and Fluorine Al+3 F-1 ——- = 1 Atom ——- = 3 Atoms +3 -3

Covalent Compound:
Formula’s for Ionic and Covalent both resemble the same for look wise. You will be able to figure out the formula by looking at the prefixes.
Ex/ Dinitrogen Tetrachloride . N Cl . 2 4