AOS 1 Practise Thread

[dinosaur93]

1. In which of the following lists of species is the oxidation number of the nitrogen atoms the same?

A.
B.
C.
D.

Shouldnt the answer be D?



2. Which of the following chemical equations represents a redox reaction?

A.
B.
C.
D.



3. A mixture of 6 mole of aluminium powder and 3 mole of hydrogen chloride gas was added to a container and allowed to react according to the equation:

The number of mole of gas remaining in the container when the reaction is complete would be:

A. 2.5 mole
B. 5.0 mole
C. 7.5 mole
D. 15 mole.

How was the answer derived to A?



4. Which of the following is a balanced half equation?

A.
B.
C.
D.

How was the answer derived to D?


5. When sulfuric acid was added to a partucular white substance, magnesium sulfate, water and a colourless gas were formed. The gas, when added to limewater turned it milky. The unknown white substance was most likely to be . Explain why.
 

[g1na]

In question 1, i got D as well :S

2) im saying it's D

3) the answer A is correct

working:
 this involves finding the reactant which is in excess and limiting. In this case, HCl is limiting, you would then find out the moles of AlCl3 adding it to the moles of H_2 giving you 2.5 mol

4) D doesn't seem to be right because wouldnt you have to add H2O to balance out the oxygens? so not sure about that

5) are you sure it's MgO because is MgO reacted with H2SO4 wouldnt that just make MgSo4 and water?
im pretty sure they meant MgCO3 and from that it would produce carbon dioxide to react with CaCo3 to make a milky colour solution

so yeah correct me if im wrong but that's what i think

[Phy124]

1. In which of the following lists of species is the oxidation number of the nitrogen atoms the same?

A.
B.
C.
D.

Shouldnt the answer be D?

What does it say the answer is? I would have also gone with D 

4. Which of the following is a balanced half equation?

A.
B.
C.
D.

How was the answer derived to D?

None of those look right to me...

From what I can remember the real reactions for those above would be:

A.
B.
C.
D.