Acids & Bases

Properties of acids:
-Tastes sour
-pH lower than 7
-neutralize bases
-turn litmus paper into red
-corrodes metals

Properties of bases:
-Tastes bitter
-pH more than 7
-neutralize and bases
-conducts electricity
-slimy


Name 2 acids and their uses:
-Used in car batteries
-Food industries

pH scale:
Acid: pH 1-7
Neutral: pH 7
Bases: pH 8-14

Acid + Base ---> Salt + Water
Examples:  HCL + NaOH --> NaCl + H20
H2SO4 + CaOH ---> CaSO4 +H20


Acid + Metal --> Hydrogen + Salt
Examples: HCL + Mg ---> MgCl + H2
H2SO4 + Al ---> AlSO4 +H2

Acid + Metal Carbonate ---> Water + Salt + Carbon dioxide
Examples:  2HCl + 2MgCO3 ---> H20 + 2CO2 +2MgCl

Electrolysis

Chemistry

Topic: Electrolysis

What is it? 

Electrolysis uses an electricity to break down ionic compounds to form element, both reduction and oxidation takes place, so electrolysis is a redox reaction, during the reaction metals and gases my form on the electrode.

Ionic substances from when a metal reacts with a non-metal, for example sodium chloride forms when sodium reacts with a chlorine. It contains the positively charged sodium ions and the negatively charged chlorine ions.

Keywords:

-Electrode:

They are commonly made from inert materials, such as graphite and platinum, they are used to attract the cations and anions.

-Cathode:

The negatively charged 

electrode, it attracts positive ions (cations).

-Anode: 

The positively charged electrodes, it attracts negative ions (anions).

What is oxidation and reduction?

Reduction. When positively charged ions move to the negative electrode during the electrolysis. They receive electrons.

Oxidation: When the negatively charged ions move to the positive electrode during the electrolysis. They lose electrons.

How does electrolysis happen?

For electrolysis to work, the ions have to be able to move. The ions in the ionic substance are free to move when it is dissolved in water. For example if you're doing an electrolysis of CuSO4 in water.

-Cu has  a positive charge of +3.

-SO4 has  a negative charge of -2.

-OH has a negative charge of -1.

-H has a positive charge of +1.

The positive ions  (cations) will go to the cathode, while the negative ions (anions) will go to the anode. So, the copper and hydrogen will go to the cathode, while the hydroxide and sulphate will go to the anode.

What happens in the anode:

The more reactive element will stay in the solution, while the less reactive will return to its original form. So, hydrogen is more reactive than copper, the hydrogen will stay in the liquid, while the copper will return to its original from which is solid, the copper will start appearing on the anode.

What happens in the cathode:

The more reactive will stay in the solution, while the less reactive will return to its original form. So, hydroxide is more reactive than sulphate, the hydroxide will stay in the solution, while the sulphate will return to its original form, which is oxygen gas.

An easier way to remember oxidation and reduction?

Oxidation

Is

Loss

Reduction

Is

Gain

What is REDOX?

It is a reaction when both reduction and oxidation happens at the same time.

My group’s experiment:

In my group I did an experiment about electrolysis in LiCl solution.

Lab setup:

So we need 2 pencils, 2 wires and a power supply.

Elements present:

Li – Lithium

Cl – Chlorine

H – Hydrogen

OH – Hydroxide

What happens in the anode and cathode?

-Cathode (-):

The lithium and hydrogen will go to the cathode because they both are positive charged, and they are attracted to the negatively charged electrode, which is the cathode. Lithium is more reactive, so it stay, but hydrogen is less creative, so hydrogen will turn into its original form which is gas, and so hydrogen gas is produced.

-Anode (+):

The chlorine and hydroxide will go to the anode, the chlorine and hydroxide are negatively charged so they will go to the positive charged, which is the anode. OH is more reactive, so it stays  in the solution, but chlorine is less reactive, so chlorine will become its original form, which is gas, which means chlorine gas is produced.

Covalent Bonding

Monday, April 21, 2014

Covalent Bonding

Covalent bonding is a bond between non-metal with non-metal. It is different from Ionic bonding because, ionic bonding is  a bond between metal and  non-metal. In ionic bonding, the ions metal donate the ions to the non-metal to make a complete valence shell, while in covalent bonding the, the ions share the electrons together.

There are single bonds, double bonds and triple bonds. Double bonds can occur between 2 atoms of oxygen, and triple bonding can happen between two atoms of nitrogen. Covalent bonds doesn’t involve charged particles.

Example of covalent bonding:

Ionic bond

Ionic bond is the electrostatic attraction of positive and negative ions to each other. The metals and non-metals bond with each other to completely fill their outer shells and become stable, because before the metals and non-metals bond, the metals and non-metals have incomplete outer shells so they are unstable.

The ionic compounds are compounds that contain ions. The compounds are usually formed between metal and non-metal.

ionic bonding

Ionic Bonding

Today I learned about ionic bonding. Ionic bonding is when two elements are used to form new elements. Ions are an atom or molecule, that is the electric charge of certain compounds or elements. The goal for the electrons is to achieve an equal number of valence like the Noble Gases.

In an element there are two electrons in the first shell, and 8 electrons in the second shell until the final shell.

For example the electric charge of Oxygen:
Oxygen has a valence (last shell) of 6 electrons. So, to make the number of electrons equal like the Noble Gases, it's easier to gain electrons. So, 8-6=2. The charge of oxygen is -2.

Now, there are also other examples of element with positive charges, like sodium.
Sodium's atomic number= 11electrons
Sodium has a valence of= 3 electrons

Since sodium only has a valence of 3 electrons in the outer shell, it's easier to lose electrons, since th goal for the electrons is to achieve an equal number of electrons like the noble gases.
So, sodium has a charge of +3.

Reflection about Moles

Moles are massive numbers, they are equal to 0.012 kg of carbon-12. Moles are the unit of a substance. There are formulas used in moles. Molar mass are also related to moles as they are also part of the formula. Molar mass has the same numercial value as the Ar or Mr.

The formulas are:

"Simple Balanced Equations" Reflection

L.O: Construct a word equation and simple balanced equations

I learned how to balance equations in chemistry. It's a bit difficult at first, since I keep on getting confused what number should I put to balance the equation, because when I put  like a certain number I might get it wrong, when I see the result as not balanced.

Example:

2   AgI   +  Na2S  ----> Ag2S + 2 NaI

Ba3N2   +  6H20 -----> 3 Ba(OH)2   + 2NH3

Well, in the end I learned a trick of how to do it quick though, I learned how to balance the equation and that is by looking at the numbers that I put in each element.

Molecular mass reflection

Today I reviewed about molecular mass. Molecular mass is the sum of atomic masses in elements, to predict the mass of the compound. To find the molecular mass, first I had to find the atomic mass of the element first and that is by looking at the periodic table.The unit used in molecular mass is grams/ mole.

Example:

Chemistry Reflection, Ar and Mr

Relative Atomic Mass (Ar):
It is the average mass of an atom in an element. For example: Na=23g/mol

Relative Molecular Mass (Mr):
It is the sum of masses of elements present in a compound. The relative molecular mass can be used to predict the mass of the product of certain elements.

Ex: CO2
C=12 x 1= 12
O=16 x 2= 32
 32+12=44 g/mol

SO4
S=32 x 1= 32
O=16 x 4=64
64+32=96 g/mol

H20
H= 1 x 2=2
O=16 x 1=16
16 +2= 18 g/mol

Reflection #3

L.O: Deducing the chemical formula of a compound from the relative number of atoms present.

I learned how to identify the number of atoms in a compound. I learned how to identify elements that is present in a compound.

Example:

Reflection about Naming Ionic Compounds

Ionic Compounds

I learned about naming ionic compounds ionic compounds are elements that are metal+nonmetal. Ionic compounds doesn't need any prefix, in naming ionic compounds I also learned the molecular formula of the ionic compounds, I learned that the elements have charge, and that the charge can be written in the result. I learned that the charges switch during the ionic compound.

For example:

Metal+ Nonmetal

Magnesium + Oxygen= Magnesium Oxide

Mg + O= MgO

Chemistry Learning ABOUT ME

Goals for Chemistry this year? How do I plan to achieve them?

My goal for chemistry this year is to get an average grade of 9.3 +  in the report. My goal is to achieve 100 in quizzes and to be able to understand every single topic. I plan to achieve my goals by studying a lot, reviewing of what I learned, so I my understanding about the topic will get better and better, and also to do my best in doing experiment and projects, I plan to achieve them also by using my time wisely, make sure I submit the HWs or projects at least one day before the due date, so I won’t stress out. I also plan to achieve them by asking questions about the topic to the teacher, in case I didn’t understand it that well yet.

Strength and Weaknesses?

My strength is when I’m being taught orally, I can get a lot of information by being taught orally and by having notes. I have strength in studying for quizzes, because I asked questions to the teacher, if I don’t understand the topic. I have weaknesses in doing experiments, because I don’t trust myself doing it, sometimes I’m just scared that I would messed up, because I don’t actually feel like I can do the experiment, during the past few years I also encounter this problem, because I’m afraid I’ll mess up and I get stressed up if I can’t do the experiment correctly.

Things I would like to do more in class?

I would like to do more oral reviewing in class, as it helps me to understand well,  I’m used to understand oral reviews well, but experiments I don’t think so, I don’t fancy experiments sometimes.

How can the teacher help to improve my learning experience?

Well, experiments sometimes, as I can understand the topic also when it was being showed, it’s just that sometimes I felt left off when doing the experiments, like I don’t understand the full topic sometimes, I’d like to be help by making explanation better to me, so I can understand more in class.