chemistry

Question 1

BASIC BEHAVIOUR : Metal oxides and hydroxides

What ions accept bases and what are these ions referred to as?

Answer 1

Bases are substances that accept hydrogen ions, H+ and these iosn are referred to as proton receptors

Question 2

Name two types of bases

Answer 2

Metal Oxides and Metal Hydroxides

Question 3

Metal Oxides

What does oxide ions accept and what is an example of this??

Answer 3

Oxide ions in metal oxides accept protons and neutralise acids and an example is calcium oxide neutralises with sulfuric acid to form calcium sulpahte

Question 4

What is calcium oxide used in and why is this important?

Answer 4

It is called lime and it is help to neutarlise acidic soils and this is important because when PH is too low, the plants tend to absorb toix ions and this hinders their root growth

Question 5

Amphoteric acids

What is an amphoteric oxide?

Answer 5

An amphoteric oxide can behave as either a base or an acid depending pn what subatnce it is reacting with

Question 6

Give an examples of amphoteric acids??

Answer 6

• Aluminium Oxide
  -It doesn’t dissolve in water but when it reacts with an acid, it forms salt and water in a similar way to other metal oxides . Inwarm conditions it will react with HCL.
  -it will also react with bases to form aluminates . For instance it will react with NaOH to form ( sodium tetrahydroxoaluminate) which is used in the bayer process to convert mineral bauxite into aluminium oxide

Question 7

Metal Hydroxides

what do metal oxides form when they react with water?

Answer 7

The reaction forms Hydroxides.

Question 8

What does hydroxides ions accept?

Answer 8

They accept protons and neutalise acids

Question 9

What is magnesium Hydroxide used for and what are the symptoms it helps relieves?

Answer 9

• Magnesium Hydroxide is used as an antacid to relieve the symptoms of indigestion and heartburn by neutralising hydrochloric acid that has entered the oesophagus

Question 10

what is calcium Hydroxide used for?

Answer 10

• It is used to neutralise acidic effluent in the chemical industry i.e dilute solution od sulfuric acid in waste water from manufacturers of polymers

Question 11

Aluminia

what is aluminia?

Answer 11

• Aluminia is a form of aluminium oxide found in the mineral bauxite

Question 12

what are properties of alumina??

Answer 12

• it is an ionic compound
  -it has high melting point due to it’s strong ionic bonds.
• It does not conduct electricity unless it is molten
  It is extracted and purified using the bayer process
  It is 8 times less the thermal conductivity of the normal aluminia

Question 13

What is the stages of the bayer Process??

Answer 13

• First bauxite is crushed
  -Then it reacts with Sodium hydroxide (aqueous state) at 170c to form sodium aluminium hydroxide
• After this, the impurities formed are filtered out
  -This is then allowed to crytallise and form aluminium Hydroxide.
• Lastly, this is heated in the rotary kiln to form (Al2o3)

Question 14

what process is alumina used in and what does it form?

Answer 14

• Alumina is used in the the Hall - Herlout process to form aluminum in electrolysis

Question 15

What other material is alumina used in and why??

Answer 15

• It is used in refractory material in Kilns and these materials retain their strength and a re chemically stable at high temperatures

Question 16

Where are transition metals found in the periodic table?

Answer 16

They are found in the central block of the periodic table and they form stable ions with incomplete d-sub shell

Question 17

Why are Sc and Zn not classified as transition metals?

Answer 17

• They are classified as d-block elements but not transition metals because their stable ions contain either a full or empty d-sub shell

Question 18

What are physical properties of transition metals

Answer 18

• having a high melting point and boiling points
• having high densities
  -are good conductors of heat and electricity
  -are stronger and harder than group 1 and 2 metals

Question 19

What are chemical properties of transition metals?

Answer 19

• form coloured compounds
• can exist in variable oxidation states
  -can behave as a catalyst
• form coloured compounds that act as a catalyst
• react with ligands to form complex ions

Question 20

What is a complex ion

Answer 20

Complex ions form when a ligand bonds to a metal ion using a dative covalent bond

Question 21

What is a ligand ?

Answer 21

A ligand is a species that has at least one lone pair of electrons that it can donate to the metal ion to form the dative covalent bonds to six water molecules

Question 22

What is an example of ligand and what is the name of this complex ion?

Answer 22

• When copper sulphate dissolves in water , the copper ions break away from the sulphate ions and form dative covalent bonds to six water molecules and the name of this complex ion is ( hexaaquacopper (II) ion

Question 23

‘G.

Question 24

Transition Metals as catalyst

What are the two types of transition metals as catalyst called?

Answer 24

Heterogenous and Homogenous

Question 25

what do catalyst do?

Answer 25

They help speed up recations by providing alternate mechanisms for the reaction, thus lowering the activation energy.

Question 26

what is the Haber process used to do?

Answer 26

it is used to make ammonia from nitrogen and hydrogen

Question 27

# haber process what does this process require?

Answer 27

- it requires a tempertaure of 400*C to increase the rate of reaction - A pressure of 200 atm to increase the yield of product made - Nitrogen and Hydrogen need to be recycled - Hetergenous catalyst of iron that helps speed up the rate of reaction

Question 28

what is a homogenous catalyst?

Answer 28

- A homogenous catalyst is when the ctalayst is in the same physical state as the reactants

Question 29

what are key components of an homogenous catalyst?

Answer 29

-same state as reactants - speeds up the rate of reaction - is an intermediate reaction ( temporaily reacts with reactants to create a new substance, which breaks it down to give the final product which then causes it to regenerate) - catalyst can be reused as it is not fully used up

Question 30

# heterogenous catalyst what is a heterogenous catalyst?

Answer 30

- occurs in the haber process - Heterogenous catalyst is a iron catalyst that is in a different physical state (solid) to it's reactants (gas)

Question 31

what occurs during the process of heterogenous calatlyst?

Answer 31

- Reactants absorb the surface of the catalyst - causes bonds in reactants to weaken and thus causes a reaction to occur - products then desorb from the catalyst surface

Question 32

what is the contact process used for?

Answer 32

it is used to make sulfuric acid

Question 33

How is sulfur trioxide produced in the contact process?

Answer 33

- It uses vanadium oxide as a heterogenous catalyst in the reaction to form sulfur oxide

Question 34

How is sulfuric acid made?

Answer 34

- sulfur is burnt in oxygen to form sulfur dioxide in a fast reaction - then sulfur trioxide forms and then it is mixed with water to form sulfuric acid

Question 35

# Formulae in organic chemistry what are molecular formulas?? What are examples of molecular formulas?

Answer 35

- They tell you the number and type of atom that is within a molecule . It will give you no information as to how atoms are arranged within molecules . - butane C4H10, contains 4 carbon atoms and 10 hydrogen atoms

Question 36

what are structural formulas?

Answer 36

- They show how all atoms are arranges but it does not require all the bonds to be shown