10 posts • Page 1 of 1
The past two weeks we have gone over questions about solving for both the Empirical and Molecular formula. I understand how to solve these problems when I am given the molecular compound and molar mass. How do I go about solving the problem if I am not given the molecular compound?
Say for example problem F.13 where 4.14 g of phosphorus is combined with chlorine to produce 27.8g of a white compund. The problem then ask to find the empirical formula. What would be the steps to solve this problem?
Okay I found an example of what I was referring to. The questions states "A combustion analysis was conducted on an unknown molecule. After 28.4 grams of the unknown molecule was combusted, 43.82 grams of carbon dioxide and 16.44 grams of water were produced. The molecular mass of molecule is 342.3g/mol. What is the empirical formula of the unknown molecule?" I was wondering if anyone could help me with steps in order to solve this problem.
First I would solve for the number of moles produced for each product but break it down to C,H,O. Then divide each of the moles you got by the lowest number of moles produced. Then you would use those values for the empirical. To find the molecular formula, just divide the given molecular mass by the molecular mass you calculated from the empirical. Then multiply that number by the empirical to find the molecular.
For combustions problems, you most likely need to use Avogadro's constant to find mols before proceeding to find the mass percentage. Also, if you haven't already, sign up for peer learning sessions with AAP. We went over this last week.
Who is online
Users browsing this forum: No registered users and 2 guests