Module 2 Foundations in Chemistry Flashcards
How does a temporary dipole dipole interaction occur
2 Non - Polar molecules creates an instantaneous dipoe
This induces a dipole in an atom
The attraction between 2 dipoles is called an LDF
What 3 elements form Hydrogen Bonds and why
Fluorine, Chlorine and Iodine as they’re very electronegative
What is different about compounds with Hydrogen Bonds
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
What is a linear atom nd what is the angle
2BP 0 LP –> 180 degrees
What is a triganol planar molecule and what is the angle?
3BP 0 LP Angle - 120degrees
What is a tetrahedral molecule and what is the angle
4BP O LP Angle - 109.5 degrees
What is a triganol byprimdal molecule and what is the angle
5BP 0LP Angle 2 is 90 3 is 109.5
What happens to the bond angle everytime a LP Is added
Decreases by 2.5degrees
What is the name for each LP added after tetrahedral
Tetrahedral – Triganol Pyrimidal – Non- Linear
What 3 atoms form dative covalent bonds
Boron TriFluoride, ammonium and carbon monoxide
What is special about Born Trifluoride
It only has 6 electrons in the outer shell
What is the defentiion of electronegativity
The ability of atoms to attract bonding pair of electrons in a covalent bond
What is the trend of electronegativity across a periodic table
More electronegative up the table as smaller radisu and more electronegative across the table as there is a larger nuclear charge
What do polar molecules have
An Overall Dipole
What happens to symmetrical atoms
They cancel eachother out so there is no overall dipole
What are the ion charges for:
Sulfate
Nitrate
Carbonate
Phosphate
Ammonium
SO4 2-
CO3 2-
NO3 -
PO4 3-
NH4 +
What are the defenitions for:
Relative atomic mass
Weighted mean mass of an atom of an element compared to 1/12th the mass of C-12
What is the defenition of relative isotopic mass
Mass of an atom of an isotope of an element compared to 1-12th the mass of C-12
Defenition of molecular mass
The average mass of a moleucle compared to 1-12th the mass of C-12
Defenition of relative formula mass
The average mass of a formula unit compared to 1-12th the mass of C-12
Formula for ideal gases and conversion units
pV = nRT
P = pressure in Pa (x1000 if kPA)
V = vol in m^3
n = mol.
R = 8.314
T = in K. ( add 273)
What is 1 atm. in pa
100,000 Pa
What are the 2 formulas for conc.
Mol / vol
Mass / vol
What is the formula for dilution
C1V1 = C2V2
What is the defenition for emperical formula
Simplest whole number ratio of atoms of each element present in a compound
Why is it good to have a high atom economy
Little to no waste products and the process is more economcially viable ahd helps to preserve raw materials
How would you:
Measure mass
Measure vol. of a solution
Measure gas produced in a reaction
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
What is an acid and alkali
Acid –> Proton Donor
Alkali –> Proton Acceptor
What is the defenition of strong and weak acid
Strong –> Fully dissasociates in aqueous solution
Weak —> Partially dissasosicates in aqeuous solution
What are the reations of acids with bases
Acid + Carbomate –> Salt + Water + Carbon Dioxide
Acid + Metal Oxide –> Salt + Water
Metal + Acid –> Salt + Hydrogen
Whta is a base
Substance which readily accepts H+ ions
How to prepare a solution
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
What is a procedure that obtain graph of total mass against time
Use flask, balance and stopwatch and record at time intervals between 10 and 50s
How could a student obtain sample of magnesium phosphate and reacting magneisum with phosphoric acid
Filter to obtain solid precipitate
Dry solid to remove water
How would you reducre uncertainty
Use balance with more decimal places
Use a larger mass
How would you make sure all water of crystalisation is removed
Heat to constant mass
What is the defenition of an ionic lattice
Repeating pattern of oppositely charged ions
What is the defenition of a covalent bond
Shared pair of electrons
What is meant by the term standard solution
A solution of a known concentration
How do you reduce random error in a titration
Repeat titration until you achieve concordant results within 0.1cm^3 of eachother
Calculate a mean titre from your achieved concordant results
