Year 10 term 2

Question 1

State the avogadro constant

Answer 1

6.02x10^23

Question 2

Define a mole

Answer 2

an amount of a substance

Question 3

State the formula linking molar mass, mass and moles.

Answer 3

n=m/M

(mole=mass/molar mass)

Question 4

Percentage yield=

Answer 4

actual/theoreticalx100

Question 5

Na MP and NaCl MP

Answer 5

sodium:
M1 – positive ions/cations/Na+ and (delocalised/sea of) electrons
IGNORE metal ions
M2 – (electrostatic) forces/attraction between positive
ions/cations/Na+ and
(delocalised) electrons
IGNORE references to metallic bonding
sodium chloride:
M3 – positive and negative ions/cations and anions / Na+ and Cl—
(ions)
M4 – electrostatic forces/attraction between (oppositely
charged/positive
and negative) ions / cations and anions / Na+ and Cl—
IGNORE references to ionic bonding
comparison:
M5 - forces in Na are weaker (than forces in NaCl) can be awarded
even if an
incorrect description of the forces has been

Question 6

Does Cl- exist?

Answer 6

(add dilute) nitric acid
M2 - (add aqueous) silver nitrate
M3 - white precipitate / solid / suspension

Question 7

sumn fizzed what compound of sodium could it be

Answer 7

Sodium carbonate

sodium hydroxide is soluble

Question 8

Potassium bromide can be made by reacting potassium with bromine gas.
Explain why it is difficult to be sure whether the reaction between potassium and
bromine gas would be more vigorous than the reaction between sodium and
chlorine gas.

Answer 8

potassium is more reactive than sodium
M2 - (but) bromine is less reactive than chlorine

Question 9

Hydrogen chloride gas dissolves in water to form solution A.
Hydrogen chloride gas dissolves in methylbenzene to form solution B.
A teacher adds a piece of magnesium ribbon to each solution.
Explain why she observes effervescence with solution A but not with solution B.

Answer 9

(effervescence) due to hydrogen (gas)
solution A is acidic / contains H+
/ contains hydrochloric acid
solution B is not acidic / does not contain H+
/ does not contain hydrochloric acid

Question 10

Explain how the covalent bonds in the water molecule hold the hydrogen and
oxygen atoms together.

Answer 10

(strong electrostatic) attraction between
bonding/shared pair of electrons
and nuclei (of hydrogen and oxygen)

Question 11

buckminister

Answer 11

weak intermol

Question 12

why silicon dioxide high MP?

Answer 12

(covalent) bonds have to be broken
M2 – large amount of energy required
/ bonds are strong

0/2 for intermol

Question 13

Describe the metallic structure of molybdenum.

Answer 13

(giant structure of) positive ions
(surrounded by) delocalised electrons

Question 14

Suggest why buckminsterfullerene has a much lower melting point than diamond

Answer 14

Any two from:
Not a giant structure
IGNORE simple molecular
Weak intermolecular (forces of ) attraction /
weak (forces of) attraction between molecules /
weak van der Waals (forces of attraction)
between molecules
No covalent bonds break (when melting)