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Welcome to Chemtopper.com - Free Chemistry Help forum.
This forum has been created to help out students who need help in Chemistry. You are welcome to post your questions here which will be posted in no time.
Please feel free to ask questions here and also answers the questions posted by others to help them out.
October 15, 2017, 02:58:48 PM by rajive | Views: 8 | Comments: 0

Hi I have following queries
Q1 - Arrange in the order of increasing ionic radii in water and their mobility Be2+, Mg2+, ca2+, Sr2+
Q2 - Why crystalline sodium peroxide is highly hygroscopic in nature
Q3 - What is chleating effect
Q4- Which one has the highest and lowest melting point and why - Nacl, kcl, Rbcl, CsCl
Q5 - Why is anhydrous HCL predominantly covalent in gaseous state but is ionic in aqueous state
Q6 - Which of the following is incorrect
       a) In CF2=C=CF2 molecule of all four flourine atoms are not in the same plane
        b) Ka2 of fumaric acid is more than Ka2 of maleic acid due to intramolecular hydrogen bonding in maleic acid
         c) The O-O bond length in O2[AsF4] is longer than Ko2
          d) The bond angle order in -S-halogen is OSF2 <OSCl2 < OSBr2
Q7 - Why crystals of hydrated calcium sulphate are soft and easily cleaved where as anhydrous calcium sulphate are very difficult to cleave
Q8 - CO Forms Weak bonds to lewis acid such as BF3. In contrast CO forms strong bonds to transition metals. Explain
October 11, 2017, 03:55:02 AM by Jared | Views: 12 | Comments: 1

What are the specific bonds are present when an Epidermal Growth Factor (EGF) ligand interacts with an Epidermal Growth Factor Receptor (EGFR)?
October 09, 2017, 09:04:45 PM by lakshmi | Views: 11 | Comments: 1

Dear Dr. Uma,
 I was unable to get the correct answer for this question. I tried various different ways, but still am not able to get it. Please let me know...
Thank you.
October 09, 2017, 07:44:43 PM by lakshmi | Views: 12 | Comments: 1

For this question, the enthalpy combustion of graphite(carbon) and the enthalpy combustion of hydrogen should be negative right? Because they are exothermic reactions?
I was unable to copy paste the question so I have attached it as a file.
Please kindly let me know.
Thank you,
Lakshmi
PS question is here
Calculate the enthalpy of combustion of methane, given that the enthalpy of formation of methane is -74.6 kJ/mol and the enthalpy combustion of graphite and hydrogen are 393.4 kJ and 285.7 kJ/mol respectively.
October 08, 2017, 11:09:20 PM by lakshmi | Views: 16 | Comments: 1

Question is attached as picture as it is from Quiz 6.3
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