# A level Chemistry problem

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#1
Qq
Last edited by lesliesundays; 3 months ago
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3 months ago
#2
(Original post by lesliesundays)
Guys I’m stuck of these 2 questions pls help:

1) 2SO2(g) + O2(g) ——->. 2SO3(g)
<——-
In an experiment, 2.00mol of sulfur dioxide are mixed with 2.00mol of oxygen. The total amount of the three gases at equilibrium is 3.40mol.
What is the mole of sulfur trioxide in the equilibrium mixture?

2) a 0.10moldm-3 aq solution of an acid is slowly added to 25cm3 of a 0.10moldm-3 aq solution of a base. Which acid base pair has the highest pH at the equivalence point.
For Q1, let the amount of moles of O2 that reacted be x.

this means that moles of SO2 that reacted would be 2x since SO2 : O2 ratio is 2:1.

similarly this means that x moles of O2 will react to form 2x moles of SO3, since O2 : SO3 was 1 : 2

Now, let us look at initial vs final concentrations.

initially you have 2 moles of O2. X moles react. So finally you have (2 - x) moles of O2.

initially you have 2 moles of SO2. 2x moles react. So you finally have (2 - 2x) moles of SO2.

initially you have 0 moles of SO3. 2x moles are formed. So you finally have 2x moles of SO3.

question tells you that finally at equilibrium, the sum of all moles is 3.4.

this means final moles of SO2 + O2 + SO3 = 3.4
which will be (2 - 2x) + ( 2 - x) + (2x) = 3.4
Solve for x and you get 0.6

But moles of SO3 is 2x. So answer is 2 x0.6 = 1.2
0
3 months ago
#3
(Original post by lesliesundays)
Guys I’m stuck of these 2 questions pls help:

1) 2SO2(g) + O2(g) ——->. 2SO3(g)
<——-
In an experiment, 2.00mol of sulfur dioxide are mixed with 2.00mol of oxygen. The total amount of the three gases at equilibrium is 3.40mol.
What is the mole of sulfur trioxide in the equilibrium mixture?

2) a 0.10moldm-3 aq solution of an acid is slowly added to 25cm3 of a 0.10moldm-3 aq solution of a base. Which acid base pair has the highest pH at the equivalence point.
Question 2 must be an mcq ?? What were the other options
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