{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

Scan_Doc0097 - Formula from Empirical Formula • Obtain...

Info icon This preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
n, the atoms ~15N3' e al- t can - . To ula, - ers very close to whole numbers, -- as 9.92 and 1.08, should be ed to whole numbers. Numbers -- as 2.25, 4.33, and 2.72 should not nded to whole numbers. 3.7 Determining the Formula of a Compound 93 PROBLEM-SOLVING STRATEGY Empirical Formula Determination • Since mass percentage gives the number of grams of a particular element per 100 grams of compound, base the calculation on 100 grams of compound. Each percent will then represent the mass in grams of that element. • Determine the number of moles of each element present in 100 grams of compound using the atomic masses of the elements present. • Divide each value of the number of moles by the smallest of the values. If each resulting number is a whole number (after appropriate rounding), these numbers represent the subscripts of the elements in the empirical formula. • If the numbers obtained in the previous step are not whole numbers, multiply each number by an integer so that the results are all whole numbers. PROBLEM-SOLVING
Image of page 1
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: Formula from Empirical Formula • Obtain the empirical formula. • Compute the mass corresponding to the empirical formula. • Calculate the ratio Molar mass Empirical formula mass • The integer from the previous step represents the number of empirical formula units in one molecule. When the empirical formula subscripts are multiplied by this integer, the molecular formula results. This procedure is summarized by the equation: . . molar mass Molecular formula = (empirical formula) x ---------empirical formula mass XAMPLE 3.10 Determine the empirical and molecular formulas for a compound that gives the following percentages on analysis (in mass percents): 7l.65% Cl 24.27% C 4.07% H The molar massis known to be 98.96 g/mol. Solution Where are we going? • To find the empirical and molecular formulas for the given compound What do we know? ./ Percent of each element ./ Molar mass of the compound is 98.96 glmol...
View Full Document

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern