Qualification > Sciences

chem. questions

(1/3) > >>

sweetie:
cud sum1 xplain to me Q 7,12,16,20 and 24 of nov05 P1

Thank You ;)

Saladin:
Q7:

The greater the difference in pH, the greater the enthalpy chage. So tha answer is A.

Q12:

The answer is D. Because MgO takes moles. Al2O3 takes mol, and Sulphur takes a lot of moles, because Sulphur can form SO2, then SO3.

Q16:

The answer is C. You need to have a base avaiable when you react it with a Carbonate. So it is wither C or D. Now the answer is not D, because MgCO3 and CaCO3, are both weak carbonates because both metals have strong positive charges and small radii. So, the answer is C, because Barium Carbonate would not easily decompose under heat.

Q20:

The answer is B. Cis and trans of this: CHCl==CHCl and CH2==CCl2. Total, 3.

Q 24:

A. It could be between the 2 middle carbon, between either one of the side carbons.

Hope that explanation is suffice.

sweetie:

--- Quote from: The Dude 321 on April 27, 2010, 07:41:54 pm ---Q7:

The greater the difference in pH, the greater the enthalpy chage. So tha answer is A.

Q12:

The answer is D. Because MgO takes moles. Al2O3 takes mol, and Sulphur takes a lot of moles, because Sulphur can form SO2, then SO3.

Q16:

The answer is C. You need to have a base avaiable when you react it with a Carbonate. So it is wither C or D. Now the answer is not D, because MgCO3 and CaCO3, are both weak carbonates because both metals have strong positive charges and small radii. So, the answer is C, because Barium Carbonate would not easily decompose under heat.

Q20:

The answer is B. Cis and trans of this: CHCl==CHCl and CH2==CCl2. Total, 3.

Q 24:

A. It could be between the 2 middle carbon, between either one of the side carbons.

Hope that explanation is suffice.

--- End quote ---

thanx sooo much!
but cud u xplain que. 24 a lil bit in more detail?
and for Q 12, i guess that 1 mole of Al2O3 needs 0.75 moles of O2, check it plz??????
and in 20 , u mean there r 2cis and 1 trans???

Saladin:
Question 12: One mole of Oxygen is O2. So O3 is 1.5 moles of oxygen, what you said there is the ratio.

Q 20: Yes, there are 2 cis-trans isomers. And also one where you have 2 Hs on one carbon and 2 Cls on the other.

Q24: Butan 2 can mean from the right 2 or the left 2. This will mean the double bond is able to be in 3 different positions, in the middle, and other 2 sides.

sweetie:
got it
thanx :)

Navigation

[0] Message Index

[#] Next page