Higher chemistry 2010 multiple choice help

Soo stuck and they're probably all so easy:-(!!

1)
0·5 mol of copper(II) chloride and 0·5 mol of
copper(II) sulphate are dissolved together in
water and made up to 500 cm3 of solution.
What is the concentration of Cu2+
(aq) ions in
the solution in mol l–1?
A 0·5
B 1·0
C 2·0
D 4·0

2) 1 mol of hydrogen gas and 1 mol of iodine
vapour were mixed and allowed to react.
After t seconds, 0·8 mol of hydrogen
remained.
The number of moles of hydrogen iodide
formed at t seconds was
A 0·2
B 0·4
C 0·8
D 1·6.

3)
The Avogadro Constant is the same as the
number of
A molecules in 16 g of oxygen
B ions in 1 litre of sodium chloride solution,
concentration 1 mol l–1
C atoms in 24 g of carbon
D molecules in 2 g of hydrogen.

Thanks for any help:-)!!

Reply 1

Borek

4

Show what you did. You did something, didn't you?

Technically there is no correct answer in 3rd problem, unless the question is "which of the following is the closest to the Avogadro's number".

Reply 2

rachel479

8

1) copper (II) chloride = CuCl2
copper (II) sulfate = CuSO4
Both compounds have only one Cu per formula unit, so 0.5 mol of Cu+2 would be found in each quantity.
Added together = 1 mol Cu+2 in 500 mL solution.
c=n/v
=1.0 mol/ 0.500 L = 2 mol l-1

2) H2(g) + I2(g) ---> 2HI(g)
if there is 0.8 mol H2 left after t seconds then 0.2 mol H2 has reacted. Since one mol H2 gives 2 mol HI
mol HI = 0.2 mol H2 x 2 = 0.4 mol HI

and idk about no 3, hope that helped :smile:

Reply 3

langlitz

17

Original post by rachel479

1) copper (II) chloride = CuCl2
copper (II) sulfate = CuSO4
Both compounds have only one Cu per formula unit, so 0.5 mol of Cu+2 would be found in each quantity.
Added together = 1 mol Cu+2 in 500 mL solution.
c=n/v
=1.0 mol/ 0.500 L = 2 mol l-1

2) H2(g) + I2(g) ---> 2HI(g)
if there is 0.8 mol H2 left after t seconds then 0.2 mol H2 has reacted. Since one mol H2 gives 2 mol HI
mol HI = 0.2 mol H2 x 2 = 0.4 mol HI

and idk about no 3, hope that helped :smile:

Yep your answer is correct for 1 and 2.

For 3 you need to think about which of the answers is equal to one mole
Remember that hydrogen and oxygen are diatomic

Higher chemistry 2010 multiple choice help

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