Topic 1 Chem

Question 1

What does the avagadro constant show?

Answer 1

The number of particles witching 1 mole of any element.
Number of particles= n x 5.022x10 23

Question 2

Give two equations to find Moles with units?

Answer 2

= mass/Mr
= concentration (mol/dm-3) x volume (cm3) /1000

Question 3

What is the definition of Ar?

Answer 3

The mean mass of an atom of an element

Question 4

The mean mass of a molecule of a compound?

Answer 4

The Mr

Question 5

What does relative formula mass mean?

Answer 5

The mean mass of compounds that have a giant structure

Question 6

What does empirical formula mean?

Answer 6

The simplest whole number ratio of a compound

Question 7

What does molecular formula mean?

Answer 7

The actual number of each atom in the molecules

Question 8

How to find the molecular formula?

Answer 8

1. Find the Mr of the empirical formula
2. Find the multiplier by dividing the Mr of the molecular formula by the Mr of the empirical Formula
3. Multiply the empirical formula by the multiplier

Question 9

What is molar mass, also give units?

Answer 9

A substance mass in grams per mole (g/mol-1)

Question 10

What is the formula to find a concentration using mass of solute and solvent only?

Answer 10

PPM= mass of solute/ mass of solvents 10^6

Question 11

How to find the molar volume of a gas?

Answer 11

Volume of gas in dm3= 24dm3 x number of moles

Volume of gas (cm3) = 24,000(cm3) x number of moles

( must be at room temperature and pressure)

Question 12

What is the unit of pressure in the pV=nRT

Answer 12

Pascal (p)

Question 13

What is the unit of volume in the pV=nRT formula?

Answer 13

Volume in m3

Question 14

What is the unit of moles in pV=nRT?

Answer 14

Moles

Question 15

What is the unit of temperature in the formula pV=nRT?

Answer 15

It’s in kelvin’s
So +273 if the temp is Celsius

Question 16

What is the value of R in pV=nRT?

Answer 16

R it’s always 8.31

Question 17

How to calculate the percentage yield?

Answer 17

% yield is calculated =actual/theoretical x100=

Question 18

How to calculate the % of atom economy?

Answer 18

= mr of desired products/ total of Mr of all products x 100

Question 19

Give an equation used to calculate concentration using moles and volume only:

Answer 19

= number of moles in (mol)/ volume (dm3)

Question 20

Give an equation to calculate concentration using mass and volume only ?

Answer 20

Concentration (g/dm-3) =mass (g)/ volume (dm3)

Question 21

Give a detailed definition of ionic bonding:

Answer 21

• the bonding between a metal and non-metal
  -electrons are transferred from the metal to the non metal

Question 22

What is the definition of Covalent bonding?

Answer 22

The bond between 2 non-metals, by sharing electrons

Question 23

What are the characteristics of a giant covalent structure?

Answer 23

• strong covalent bonds
• high melting point

Question 24

What are the characteristics of simple covalent molecules?

Answer 24

• have low melting point
  -weak intermolecular forces

Question 25

Describe the structure of diamond:

Answer 25

- has macromoléculaire structure made up of carbon atoms each bonded to 4 carbon atoms -strong covalent bodies - high melting point

Question 26

Describe the structure of graphite:

Answer 26

- has 1 delocalised electron per carbon atom —> which allows it to conduct electricity - has weak intermolecular forces between layers which can slide over each other making it lubricant