Chemistry: Post your doubts here!

[Metanoia]

So its like the Ester has 4 carbon atoms and we distribute them equally so 2 which is ETH ?

Exactly. So we get ethanol and ethanoic acid. And the ethanol later gets oxidized to ethanoic acid. Giving us a single product in the end.

 

[My Name]

Exactly. So we get ethanol and ethanoic acid. And the ethanol later gets oxidized to ethanoic acid. Giving us a single product in the end.

I understood
Alhamdulillah!

 

[The Chill Master]

That is the ester right?

Then the question states that Q is hydrolyzed with sulfuric acid

C4H8O2 --> acid + alcohol

Then the mixture was oxidized to obtained a single product, R, in other words, the alcohol in the above reaction is oxidized to become the same compound as the acid.

It simply means the alcohol has the same number of carbons as the acid.

We have 4 carbons to divide equally among the two....so the alcohol was ethanol and the acid was ethanoic acid.

When this mixture was oxidized, all we end up with is a sample of ethanoic acid.

And ya should in every case when we have a similar type of question should we divide equally like what will we do if we have 5 carbon atoms?

 

[My Name]

And ya should in every case when we have a similar type of question should we divide equally like what will we do if we have 5 carbon atoms?

good question
by that you mean like when they say SINGLE product?

 

[The Chill Master]

good question
by that you mean like when they say SINGLE product?

Ya

 

[Metanoia]

And ya should in every case when we have a similar type of question should we divide equally like what will we do if we have 5 carbon atoms?

In this case, we divide equally because the question gives us the information that "a single product was obtained after oxidizing."

We don't assume that we divide equally for all other questions unless the clues tells us so.

As for your example of 5 carbons, there is no way to obtain a single product after oxidizing.

 

[sid2333]

Can anybody help me out with this question?


25 Use of the Data Booklet is relevant to this question.
2.30 g of ethanol were mixed with aqueous acidified potassium dichromate(VI) and the desired
organic product was collected by immediate distillation under gentle warming. The yield of
product was 70.0 %.
What mass of product was collected?
A 1.54 g B 1.61 g C 2.10 g D 2.20 g

 

[sid2333]

26 Which pair of reactions could have the same common intermediate?
W CH3CH2CH3 → intermediate → (CH3)2CHCN
X CH3CH(OH)CH3 → intermediate → (CH3)2C(OH)CN
Y CH3CH=CH2 → intermediate → CH3CH(OH)CH3
Z CH3CO2CH2CH2CH3 → intermediate → CH3CH2CH2Br
A W and X B W and Y C X and Z D Y and Z

 

[sid2333]

14 Use of the Data Booklet is relevant to this question.
When 3.00 g of an anhydrous nitrate of a Group II metal is decomposed, 1.53 g of gas is
produced.
What is the nitrate compound?
A beryllium nitrate
B calcium nitrate
C magnesium nitrate
D strontium nitrate

 

[sid2333]

10 The enthalpy change of the neutralisation given below is –114 kJ mol–1.
2NaOH(aq) + H2SO4(aq) → Na2SO4(aq) + 2H2O(l)
By using this information, what is the most likely value for the enthalpy change of the following
neutralisation?
Ba(OH)2(aq) + 2HCl(aq) → BaCl2(aq) + 2H2O(l)
A –57 kJ mol–1 B –76 kJ mol–1 C –114 kJ mol–1 D –228 kJ mol–1

 

[Xaptor16]

can someone please help me with question 4?i know the equation is PV=nRT i just have problem finding the volume and the number of moles
the answer is A btw

 

[My Name]

 

[My Name]

correct answer is D

 

[My Name]

Answer is C

 

[Xaptor16]

View attachment 51484

what is the answer to this?

 

[My Name]

what is the answer to this?

B

 

[shazmina]

View attachment 51482

can someone please help me with question 4?i know the equation is PV=nRT i just have problem finding the volume and the number of moles
the answer is A btw

First find out the volume of M using the initial conditions that have been provided using the formula PV=nRT
Where P= 1*10^5, V=?, T= ( 20+273 ) & n =1
so this way find out the volume ..... and u will get it as 0.024 m^3( i prefer u to the carry the entire answer in the calculator )
and then consider the entire system to find the new pressure which is found by using the same formula .. but this time u know the volume of N which is 3 times the volume of M therefore
New volume of the system = ( 4* 0.024 ) , New temp = ( 100 +273 ) & n = 1...
so this way u will get the new pressure as 3.18*10^4 Pa.. ie A
Hope you got it

 

[Xaptor16]

First find out the volume of M using the initial conditions that have been provided using the formula PV=nRT
Where P= 1*10^5, V=?, T= ( 20+273 ) & n =1
so this way find out the volume ..... and u will get it as 0.024 m^3( i prefer u to the carry the entire answer in the calculator )
and then consider the entire system to find the new pressure which is found by using the same formula .. but this time u know the volume of N which is 3 times the volume of M therefore
New volume of the system = ( 4* 0.024 ) , New temp = ( 100 +273 ) & n = 1...
so this way u will get the new pressure as 3.18*10^4 Pa.. ie A
Hope you got it

but are we just assuming that n=1?

 

[shazmina]

but are we just assuming that n=1?

yes

 

[Xaptor16]

yes

oh okay, thankyou! could you help me with this too, if possible please?
6 Use of the Data Booklet is relevant to this question. In some countries, anhydrous calcium chloride is used as a drying agent to reduce dampness in houses. The anhydrous salt absorbs enough water to form the dihydrate CaCl 2.2H2O. What is the percentage increase in mass?
A 14%
B 24%
C 32%
D 36%
answer is C