chemistry

Question 1

Haber process

Answer 1

Ammonia is made and its t’s an exothermic reaction, which means it gives off heat. 5 steps

1.) H2 is obtained from methane
N2 is obtained from the air
They are pumped into the compressor through a pipe

2.) Inside the compressor, the gases are compressed to around 20 000 killopascals

3.) The gases are put under high pressure and pumped into a tank with layers of iron catalyst, heated to 450 °C. In the tank, some of the nitrogen and hydrogen react to make ammonia
- N₂ (g) + 3H₂ (g) ⇌ 2NH₃ (g)

4.) The unreacted hydrogen and nitrogen, along with the ammonia, move into a cooling tank. where the ammonia turns into a liquid and is taken out and stored in containers.

5.) The unreacted H2 and N2 gases are recycled back into the system and start over again

Question 2

Air in atmosphere

Answer 2

• 78% nitrogen
• 21% oxygen
• 0.04% carbon dioxide

Question 3

Diatomic atom

Answer 3

Molecules made of 2 atoms

Question 4

Alkenes

Answer 4

• are unsaturated (double bond) with carbon double bonds C=C
  -Covalent bond (Atoms bond to hare electrons)
• general general formula is CnH2n, 2*n, n = number of carbons, to find number of hydrogen
  -more reactive than alkanes

Question 5

Manufactre of alkenes

Answer 5

*Catalytic Cracking
- Converts long-chain hydrocarbons into shorter chains
- used to make Used to make polymers (plastics)
- Hydrogen used to make ammonia
- Kerosene and diesel oil are used to cracking to produce petrol, other alkenes, and hydrogen

Question 6

how to tell from Alkenes to Alkanes

Answer 6

• Use Bromine water (an orange colored soltion)
• When bromine water is with an alkane, the solution remains orange
• When bromine water is with an alkene, the solution will go colourless

Question 7

Alkanes

Answer 7

• Are unsaturated (single bond) with carbon double bonds C-C
  -Covalent bond (Atoms bond to share electrons)
  -Consists of non-metal atoms
• The general formula of the alkanes is CnH2n+2 (use 2*n+2 , N = number of carbons to find number of hydrogen)
  -are colourless compounds
• undergo combustion (a chemical reaction with oxygen that releases heat and light)
• Alkanes undergo complete combustion
  Form:
  Alkane + oxygen → carbon dioxide + water
• React with halogens in the presence of light in substitution reactions (replace an atom molecule)

Question 8

Avogadro Constant

Answer 8

6.02x10^23
- number of particles in one mole
- mass of 1 mole of a substance is known as the molar mass
-For an element, the relative atomic mass written in grams (g)
Avogadro Law:
* If you have the same temperature and pressure, then equal numbers of gas particles (moles) will always take up the same amount of space
- At room temperature and pressure, the volume by one mole (molar volume) of any gas was found to be 24 dm^3/ 24,000 cm^3

-Volume of gas = Moles x Molar Volume
-Number of moles of a gas = Volume ÷ Molar Volume
-

Question 8

Ionic bond/ ion

Answer 8

Ionic bond:
* the electrostatic attraction between positively charged ions (cations) and negatively charged ions (anions), formed when electrons are transferred from a metal to a non-metal.
- ion: an electrically charged atom/group of atoms formed by the loss/gain of electrons
- Negative ions are called anions and form when atoms gain electrons, meaning they have more electrons than protons
- Positive ions are called cations and form when atoms lose electrons, meaning they have more protons than electrons

-Elements in Group 1 form ions with a 1+ charge
-Elements in Group 2 form ions with a 2+ charge
-Elements in Group 6 form ions with a 2- charge
- Elements in Group 7 form ions with a 1- charge

Question 9

Electrolysis

Answer 9

• Electrolysis is a process where an electric current is used to break down a molten (liquid) ionic compound into its elements
• The process also occurs for aqueous solutions of ionic compounds
• An Electrode is a rod (usually metal or graphite) that conducts electricity into or out of an electrolyte
• Anode is the positive electrode of an electrolysis cell
• An anion is a negatively charged ion that is attracted to the anode
• A cathode is the negative electrode of an electrolysis cell
• A cation is a positively charged ion that is attracted to the cathode
• Metals and hydrogen form
• Metals and hydrogen form positive ions, either form metal/ hydrogen gas (formed at the cathode)
• If the metal is less reactive than hydrogen, then the metal is produced
• If the metal is more reactive than hydrogen, then hydrogen gas is produced instead
• Non-metals form negative ions, so non-metals are formed at the anode (execpt hydrogen)
• The power supply provides the cathode with a supply of electrons, causing it to become negatively charged
  Positive ions (cations) in the electrolyte move towards the cathode where they gain electrons
• Negative ions (anions) in the electrolyte move towards the anode where they lose electrons
• The electrons move from the anode back towards the power supply

Question 10

Ionic half equation

Answer 10

• Oxidation: the loss of electrons
• Reduction: the gain of electrons
• As the ions come into contact with the electrode:
• Ions are charged particles (either positive or negative).
• When ions gain or lose electrons, they become neutral atoms or molecules.
• At the anode, negatively charged ions lose electrons
  So, oxidation occurs at the anode
• At the cathode, the positively charged ions gain electrons
  So, reduction occurs at the cathode