Module 2 Foundations in Chemistry

Question 1

How does a temporary dipole dipole interaction occur

Answer 1

2 Non - Polar molecules creates an instantaneous dipoe
This induces a dipole in an atom
The attraction between 2 dipoles is called an LDF

Question 2

What 3 elements form Hydrogen Bonds and why

Answer 2

Fluorine, Chlorine and Iodine as they’re very electronegative

Question 3

What is different about compounds with Hydrogen Bonds

Answer 3

They’re solube in water due to -OH bonds and their melting points are higher than normal molecules and ice is less dense than water due to molecules in ice is held apart by Hydrogen Bonds

Question 4

What is a linear atom nd what is the angle

Answer 4

2BP 0 LP –> 180 degrees

Question 5

What is a triganol planar molecule and what is the angle?

Answer 5

3BP 0 LP Angle - 120degrees

Question 6

What is a tetrahedral molecule and what is the angle

Answer 6

4BP O LP Angle - 109.5 degrees

Question 7

What is a triganol byprimdal molecule and what is the angle

Answer 7

5BP 0LP Angle 2 is 90 3 is 109.5

Question 8

What happens to the bond angle everytime a LP Is added

Answer 8

Decreases by 2.5degrees

Question 9

What is the name for each LP added after tetrahedral

Answer 9

Tetrahedral – Triganol Pyrimidal – Non- Linear

Question 10

What 3 atoms form dative covalent bonds

Answer 10

Boron TriFluoride, ammonium and carbon monoxide

Question 11

What is special about Born Trifluoride

Answer 11

It only has 6 electrons in the outer shell

Question 12

What is the defentiion of electronegativity

Answer 12

The ability of atoms to attract bonding pair of electrons in a covalent bond

Question 13

What is the trend of electronegativity across a periodic table

Answer 13

More electronegative up the table as smaller radisu and more electronegative across the table as there is a larger nuclear charge

Question 14

What do polar molecules have

Answer 14

An Overall Dipole

Question 15

What happens to symmetrical atoms

Answer 15

They cancel eachother out so there is no overall dipole

Question 16

What are the ion charges for:
Sulfate
Nitrate
Carbonate
Phosphate
Ammonium

Answer 16

SO4 2-
CO3 2-
NO3 -
PO4 3-
NH4 +

Question 17

What are the defenitions for:
Relative atomic mass

Answer 17

Weighted mean mass of an atom of an element compared to 1/12th the mass of C-12

Question 18

What is the defenition of relative isotopic mass

Answer 18

Mass of an atom of an isotope of an element compared to 1-12th the mass of C-12

Question 19

Defenition of molecular mass

Answer 19

The average mass of a moleucle compared to 1-12th the mass of C-12

Question 20

Defenition of relative formula mass

Answer 20

The average mass of a formula unit compared to 1-12th the mass of C-12

Question 21

Formula for ideal gases and conversion units

Answer 21

pV = nRT
P = pressure in Pa (x1000 if kPA)
V = vol in m^3
n = mol.
R = 8.314
T = in K. ( add 273)

Question 22

What is 1 atm. in pa

Answer 22

100,000 Pa

Question 23

What are the 2 formulas for conc.

Answer 23

Mol / vol
Mass / vol

Question 24

What is the formula for dilution

Answer 24

C1V1 = C2V2

Question 25

What is the defenition for emperical formula

Answer 25

Simplest whole number ratio of atoms of each element present in a compound

Question 26

Why is it good to have a high atom economy

Answer 26

Little to no waste products and the process is more economcially viable ahd helps to preserve raw materials

Question 27

How would you: Measure mass Measure vol. of a solution Measure gas produced in a reaction

Answer 27

Mass --> Use a digital mass balance - use balance with suitable resolution Vol. for a solution --> Measure vol. of a solution and if making up standard solution, use volumetric flask for required vol. Gas produced --> Gas Syringe

Question 27

What is an acid and alkali

Answer 27

Acid --> Proton Donor Alkali --> Proton Acceptor

Question 28

What is the defenition of strong and weak acid

Answer 28

Strong --> Fully dissasociates in aqueous solution Weak ---> Partially dissasosicates in aqeuous solution

Question 29

What are the reations of acids with bases

Answer 29

Acid + Carbomate --> Salt + Water + Carbon Dioxide Acid + Metal Oxide --> Salt + Water Metal + Acid --> Salt + Hydrogen

Question 30

Whta is a base

Answer 30

Substance which readily accepts H+ ions

Question 31

How to prepare a solution

Answer 31

Weigh mass of crystals Dissolve in water Transfer to 250cm volumetric flask Make up to mark with more water so that bottom of meniscus is on the mark Use balance with 2 or more d.p Use dropping pipette when adding water up to the mark Use stopper when inverting 250cm^3 volumetric flask to mix solution

Question 32

What is a procedure that obtain graph of total mass against time

Answer 32

Use flask, balance and stopwatch and record at time intervals between 10 and 50s

Question 33

How could a student obtain sample of magnesium phosphate and reacting magneisum with phosphoric acid

Answer 33

Filter to obtain solid precipitate Dry solid to remove water

Question 34

How would you reducre uncertainty

Answer 34

Use balance with more decimal places Use a larger mass

Question 35

How would you make sure all water of crystalisation is removed

Answer 35

Heat to constant mass

Question 36

What is the defenition of an ionic lattice

Answer 36

Repeating pattern of oppositely charged ions

Question 37

What is the defenition of a covalent bond

Answer 37

Shared pair of electrons

Question 38

What is meant by the term standard solution

Answer 38

A solution of a known concentration

Question 39

How do you reduce random error in a titration

Answer 39

Repeat titration until you achieve concordant results within 0.1cm^3 of eachother Calculate a mean titre from your achieved concordant results