Sweet Apples and Oranges

Question 1

What are three diffusion experiments?

Answer 1

- Potassium manganate and water 
(in beaker)
- Ammonia and Hydrogen Chloride
(forms a white ring of ammonium chloride, nearer HCl as ammonia particles are smaller and lighter so diffuse faster)
- Bromine gas and air 
(in a jar with a glass plate)

Question 2

Simple distillation is used for…

Answer 2

separating a liquid from a solution, have to have very different BPs

Question 3

Fractional distillation is used for…

Answer 3

separating a mixture of liquids with similar BPs

Question 4

What is an isotope?

Answer 4

different forms of the same element which have the SAME no. protons and a DIFFERENT no. neutrons

Question 5

The Periodic table is an arrangement of elements in order of ….

Answer 5

increasing atomic number

Question 6

How do you find out the relative formula mass (Mr) of something?

Answer 6

Add up all the mass numbers

Question 7

What is Empirical formula?

Answer 7

the simplest formula which tells you the ratio of different elements in a compound

Question 8

What is Molecular formula?

Answer 8

tells you the actual number of atoms of each element in a molecule

Question 9

How do you calculate percentage yield?

Answer 9

percentage yield = (actual yield (g) / theoretical yield (g)) x 100

Question 10

moles in gas

Answer 10

moles = volume (dm3) / 24

Question 11

moles in terms of conc

Answer 11

moles = concentration (mol/dm3) x volume (dm3)

Question 12

What’s the electrical conductivity of Ionic compounds?

Answer 12

• only conduct electricity when molten or in solution

as when solid, ionic compounds are in a strict lattice structure and don’t have any free electrons. When the electrons are free to move when molten or in solution, they can carry an electric current and so therefore conduct electricity.

Question 13

What’s the electrical conductivity of Metallic compounds?

Answer 13

• the sea of delocalised electrons in metallic bonding means that metals are good conductors of electricity and heat

Question 14

What’s the electrical conductivity of Covalent compounds?

Answer 14

• covalent compounds don’t contain ions as they make bonds by sharing electrons, so don’t have any free charge carries and can’t carry an electric current.

APART FROM GRAPHITE, which has free electrons so is a good electrical conductor

Question 15

What is ionic bonding?

Answer 15

a strong electrostatic attraction between oppositely charged ions

Question 16

Why do ionic compounds have high melting and boiling points?

Answer 16

because of the strong electrostatic forces of attraction between oppositely charged ions

Question 17

What is the relationship between ionic charge and the MP and BP of an ionic compound?

Answer 17

The bigger the difference in charge, the stronger the attraction: if you have + and - ions they will have a weaker bond than +3 and -3 ions.

The stronger the attraction, the harder it is to break the bonds, this means that the melting and boiling points will be higher. So the bigger the charge of an ion, the higher the melting and boiling point.

Question 18

What’s an ionic crystal?

Answer 18

a giant 3D lattice structure held together by the strong attraction between oppositely charged ions

Question 19

draw a diagram to represent the positions of the ions in a crystal of sodium chloride

Answer 19

alternating Na+ and Cl- ions in a 3D lattice

Question 20

What is covalent bonding?

Answer 20

a strong attraction between the bonding pair of electrons and the nuclei of the atoms involved in the bond

Question 21

What are the two forms of covalent substances?

Answer 21

Simple molecular substances and giant covalent structures

Question 22

What are giant covalent structures?

Answer 22

like giant ionic structures but there are no charged ions.

• all the atoms are bonded together with very strong covalent bonds.
• don’t conduct electricity (apart from graphite)
• insoluble in water

Question 23

Simple molecular substances are normally …. or … at room temperature

Answer 23

gases or liquids

Question 24

Why do simple molecular substances have low MPs and BPs?

Answer 24

While the atoms within a molecule have very strong bonds, the forces of attraction between the molecules themselves are very weak.

This means that the INTERMOLECULAR forces are very WEAK and the MP and BPs are very low.

Question 25

Why do giant covalent substances have high MPs and BPa?

Answer 25

• there are lots of strong covalent bonds so you need a lot of energy to break them, meaning high MP and BP