physical chem

siewwen168 · Probably a bot. Joined: 07 Jun 2005 Posts: 1

1) Explain why carbon-12 replaced oxygen as a standard in the determination of relative atomic mass???(or why it used as a standard in determining Ar?)
Is it because carbon-12 is more available compared to oxygen,and it's easier to transport than oxygen.this is my answer,but i don;t know whether correct or not.it sounds stupid,right???

2) Haemoglobin is a protein which carries oxygen in the red blood cell. Each molecule of haemoglobin contains 4 iron atoms.If 1g of haemoglobin contains 0.00341g of iron ,calculate the RMM of haemoglobin.

3) The density of ice is 1.00gcm-3.What volume of steam is produced when 1cm3 of ice is heated to 323degree celcius(596K) at a pressure of 1 atm.(101kPa)? (1 mol gas occupies 24.0dm3 at 25 degree celcius and 1 atm.)

thanks alot for anyone who help

RobJim · Posted: Thu Jun 16, 2005 7:54 am Post subject:

1) Look at the Wikipedia entry for "atomic mass". The answer is in there. Your explanation is incorrect.

2)RMM seems to mean the same thing as molecular mass. The way you'd do this is to determine how many moles of iron atoms are in the 0.00341g of iron, and then use stoichiometry to figure out how many moles of haemoglobin you have. Then you divide the 1g by the number of moles to figure out what the mass per mole ratio is, which is the same as the molecular mass.

3) Well, first figure out how many moles of water are in the ice using density and molecular mass. Then use the Ideal Gas Law to find your answer.