OCR Chemistry F321 Exam. - [Next Tuesday[

Original post by TheFootyKing19

Hello, this is a thread made to ask questions relevant to this syllabus...

I'll start the ball rolling shall i :smile:

What is an acid?
What is an alkali?
Define Relative formula mass?
Define empiricla formula?
State and explain the shape and bond angle in h20?
Describe and explain the trend in reactivity as group 7 is descended?
How do VDW's forces arise?

1) a proton donor
2)releases OH- ions
3) is the weighted mean mass of a formula unit compared with 1/12th of the mass of carbon-12 atom.
3)simplest whole number ratio of an atom of each element.
4)104.5 - 2 bonding pairs and 2 lone pairs . electron pair repel , lone pair repel more than bonding pairs.
5)as you go down group 7 the reactivity decreases due to increase shielding effect and atomic radius and also nuclear charge increases but increase shieling and atomic radius outweighs increase nuclear charge.
6)movement of electrons , forms instantaneous dipoles and induces dipoles in neighbouring atoms/molecules.

Reply 2

OP

Awesome - Well done!

More questions...

State the name of the reaction, that is given when an element is both oxidised and reduced?
What is an orbital?
Define first ionisation energy?
Give an equation, with state symbols to show the 3rd ionisation energy of Mg?
State the name and shape of S and P orbitals?
State how many electrons occupy the first 4 shells?
What is a salt?
Describe and explain trend in boling points of Cl2, Br2, I2?
What is calcium hydroxide and magnesium hydroxide used for?
Define dative covalent bonding?
State the shape and bond angle of SF6?
Define covalent bond?
Describe and explain 2 anamolous properties of water?

Reply 3

Original post by TheFootyKing19

Awesome - Well done!

More questions...

State the name of the reaction, that is given when an element is both oxidised and reduced?
What is an orbital?
Define first ionisation energy?
Give an equation, with state symbols to show the 3rd ionisation energy of Mg?
State the name and shape of S and P orbitals?
State how many electrons occupy the first 4 shells?
What is a salt?
Describe and explain trend in boling points of Cl2, Br2, I2?
What is calcium hydroxide and magnesium hydroxide used for?
Define dative covalent bonding?
State the shape and bond angle of SF6?
Define covalent bond?
Describe and explain 2 anamolous properties of water?

1) disproportionation
2)It can hold up to 2 electrons with opposite spins
3)Energy required to remove one electron from each atom in one mole of gaseous atoms to form +1 gaseous ions under standard conditions
4)mg2+(g) to give mg3+ (g) +e-
5)s- spherical p- dumb bell shape
6)32
7)is a substance that has been replaced by a postive metal ion or NH4+
8) INCREASES due to increase number of electrons and greater intermolecular forces van der waals
9) calcium hydorxide- neutalise acidic soils magneium-neutalise acid in stomach
10)90 , octahedral
11) shared pair of electrons
12)relative high b.p so extra energy needed to break bonds
- ice less dense than liquid - more open lattice

OP

Ask me...?

Original post by TheFootyKing19

Ask me...?

ok but can you first tell me my mark

Reply 6

OP

Yeah they were all sound! Well done!

Reply 7

Original post by thefootyking19

yeah they were all sound! Well done!

define:relative isotopic mass (3)
what is the shape of f2o and explain(3)
is co2 soluble in non polar or polar solvents explain(2)
explain the trend in electronegativity across period (3)
why can nacl conduct electricity in molten but not in aqueous (2)

Reply 8

OP

Original post by otrivine

define:relative isotopic mass (3)
what is the shape of f2o and explain(3)
is co2 soluble in non polar or polar solvents explain(2)
explain the trend in electronegativity across period (3)
why can nacl conduct electricity in molten but not in aqueous (2)

1. Relative isotopic mass = the mass of an isotope compared with 1/12th of the mass of an atom of Carbon-12.

2. F20 = Non Linear - 104.5 - 2 bonded pairs, 2 lone pairs, electron pairs repel, lone pairs repel more.

3. CO2 = Non polar - as is symmetrical and so the dipoles cancel out.

4. Electronegativity decreases across a period due to, same amount of shells, with same shielding, atomic radius decreases, these factors outweigh increasing nuclear charge.

5. Nacl can coduct electricity when molten or dissolved as ions are mobile/free to move around, carrying the current. Nacl does does conduct electricity when in a solid state because the ions are not able to move around.

Reply 9

Original post by TheFootyKing19

1. Relative isotopic mass = the mass of an isotope compared with 1/12th of the mass of an atom of Carbon-12.

2. F20 = Non Linear - 104.5 - 2 bonded pairs, 2 lone pairs, electron pairs repel, lone pairs repel more.

3. CO2 = Non polar - as is symmetrical and so the dipoles cancel out.

4. Electronegativity decreases across a period due to, same amount of shells, with same shielding, atomic radius decreases, these factors outweigh increasing nuclear charge.

5. Nacl can coduct electricity when molten or dissolved as ions are mobile/free to move around, carrying the current. Nacl does does conduct electricity when in a solid state because the ions are not able to move around.

correct but question 4 is wrong electronegativity increases! because increase nuclear charge like you said outweighs increase shielding and atomic radius

OP

Thanks.

Original post by TheFootyKing19

Thanks.

no problem :wink:

my turn

Reply 12

OP

Define electronegativity?
Define successive ionisation energy?
Why is the 2nd ionisation energy of Mg greater than the first?
What is an isotope?
State the shape and bond angle of a BF3 molecule?
How can you identify that Iodide ions are present in a solution?
Give two ways that you can observe when Mg ribbon is added to HCL?

Reply 13

Original post by TheFootyKing19

Define electronegativity?
Define successive ionisation energy?
Why is the 2nd ionisation energy of Mg greater than the first?
What is an isotope?
State the shape and bond angle of a BF3 molecule?
How can you identify that Iodide ions are present in a solution?
Give two ways that you can observe when Mg ribbon is added to HCL?

1) is the measure of bonding electrons ability of attracts on in covalent bond
2) amount of energy needed to remove each electron from an atom
3) electrons closer to nucleus and electrons held more tightly by nucleus. less sheliding and atomic radius
4) are atoms that have same number of protons but different number of neutrons
5) trigonal planar -120
6) yellow ppt / is not soluble in NH3
7) fizzing , solid disappearing

Reply 14

OP

Good answers once again, your turn :smile:

Reply 15

Original post by thefootyking19

good answers once again, your turn :smile:

suggest why potassium iodide has been banned in maNy countries (1)
how can you test for presence of chlorine(2)
write an ionic equation for this(1)
does magnesium have higher m.p than al ? True/false and explain (3)

Reply 16

amz1209

hey guys,
does anyone know any limitations involved in titration experiments and how these can be improved?
also: how to improve reliability of titration
how to improve accuracy
thankss

Reply 17

OP

Original post by otrivine

suggest why potassium iodide has been banned in maNy countries (1)
how can you test for presence of chlorine(2)
write an ionic equation for this(1)
does magnesium have higher m.p than al ? True/false and explain (3)

1. As it is a radioactive isotope, which is toxic.
2. Add Silver Nitrate [AgNo3] - White precipitate will occur - completely soluble/dissolves in dilute NH3.
3. Ag+ (aq) + Cl- (aq) ---> AgCl (s)
4. False. Magnesium has a lower bp as in Aluminium the charge on the metal ion is +3, increase, the number of delocalsied electrons increases and thus the metallic bonding is stronger in Aluminium than in Mg.

Cheerio :smile:

Reply 18