I only resorted to this because for some reason the teacher cant explain why the answers are, (not all of them but some) what they are and guess its just a missprint but i thought it would be cool if you guys if you got the time to confirm this:
If you are doing yr 12 chemistry in victoria u might find these familiar...
1.
A student takes 10ml of a solution that has a PH of 5 and dilutes it by adding 90 ml of water. The hydroxide ion concentration, in mol L-1, of the new solution would be:
A 10^-5
B 10^-6
C 10^-8
D 10^-9
I believed that the Answer is C due to : Ph of 5 is [H30] = 10^-5 therefore [OH] is 10^-9 so i picked D.
Answer however is C... any input ??
2
Consider the following equillibrium that exists in water containing bromine:
Br2(aq)+ H2O(l) ---> Br^-(aq)+2H^+(aq)+BrO^-(aq)
<---
The equilibrium position could be moved towards the products by adding one drop of concentrated:
A Potassium Nitrate Solution
B Sodium Carbonate Solution
C Sulfuric Acid
D Sodium bromide Solution
I picked D but the answer was B... any reasons why?
3
Which of the following substances would give a ph of 7.0 in aqueous solution at 25 degrees?
A KNO3
B CH3COONa
C KOH
D NH4NO3
I picked d but answer is A... im not sure whats happening here... im guessing you will have to draw out equations for each one....
4
At 20 degrees and 101 kPa pressure 3.9g of methane occupies 5.88L The same volume of another unknown gaseous hydrocarbon at the same temprature and pressure has a mass of 10.7G. The unknown gas could be:
A C2H4
B C2H6
C C3H8
D C4H10
This has something to do with empirical formulas i believe. Answer is C....
5
In the reaction of 20g of Sulfuric acid with 20g of sodium hydroxide approximately:
A 20 g of Sodium sulfate are formed
B 9.1g of Sulfurik acid remains
C 9.0g of water is formed
D. 3.7g of Sodium Hydroxide remains
After balancing out the equations (which was not supplied to us and we have do make out own) it turned out to H2SO4+2NaOH -----> Na2SO4 + 2H20. It involves basic stochiometry but i am not quite sure how the correct answer is D and not C. I made out to believe that A is incorrect as actually 28g of Sulfuric Acid remained. Any idea?
6
Assuming complete conversion of sulfu dioxide into sulfuric acid, the maximum mass, in tonne, of sulfuric acid produced from 1.00 tonne (10^6g) of iron pyrites is:
A 0.817
B 1.00
C 1.07
D 1.63
Im not quite sutr which formula to apply my stochiometry on... The answer is D
7
Iron(III) Sulfide, Fe2S3, reacts with hydrochloric acid according to the equation: Fe2S3(s)+6HCl(aq) ----> 2FeCl3(aq)+ 3H2S(g)
If 20.8g of Fe2S3, is combined with 1.50L of 0.500 M HCL the expected maximum volume of H2S gas evolved, at SLC is approximately:
A 2.45L
B 7.35L
C 9.19L
D 18.45L
Correct answer is B
8
The label on a bottle of cleaning agent claims that the product contains 1.25%m/v sodium hydroxide. From this information, the mass, in g, of hydroxide ions in a 750 mL bottle would be
A 0.531
B 3.98
C 5.39
D 9.38
The answer for that is B.
9
The substance with the lowest Ph when dissolved in water is
A C2H5COONa
B C3H7OH
C CH3COOCH3
D C2H5COOH
The answer for that is D. would you look at the molar mass of these to figure it out, would you just know one is more acidic than the other? A gets crossed of straightaway as its a base correct?
10
Water that had discharged from a drain into a local creek was found to be contaminated with NAOH at a concentration of 0.0010 M. The volume of HCL solution having a pH of 1.0 that would be needed to neutralise 10L of conatminated water is:
A 0.10L
B 1.0L
C 10L
D 1.0*10^2
The correct answe is A
11
A chemist needs to adjust the ph of a 25mL of barium hydroxide solution from 10 to 8 by adding distilled water. The initial concentration of the undiluted barium hydroxide would be.
A 1.0*10^-10 M
B 5*10^-11 M
C 1*10^-4 M
D 5*10^-5 M
The correct answer is D. This one is especially tricky.. well if you got no idea whats happening like me lol.
12
A chemist analyses a 10.9 g ore sample of chalcopyrite CuFeS2. A gravimetri analysis is carried out so that all the sulfur in CuFeS2, is precipitated at BaSO4. The amount of BaSO4 is determined to be 0.10 mol. What is the percentage mass of sulfur in the ore?
A 1.6%
B 6.4%
C 16%
D 32%
Correct answer is D
And last but not least:
13
Which of the following contains the greatest number of copper ions?
A 64mg of copper nitrate
B 0.5cm^3 of metallic copper that has a density of 8.94g/cm^3
C 20ml of a 0.20 M copper(II) sulfate solution.
D 20mL of a 10% (w/v) copper(I) nitrate solution.
This involves conversions i guess. The answer is B
Well thats all of them from about a zillion questions before that
i guess cramming it down to 13 aint so bad. If anyone has any free time and would be willing to answer some of those it would be greately appreciated.
I will now be off byyyy byyyy
thanks again in advance!!