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The Mole And Moler Mass
Conversation of mass
Mole Coversation
Molar Mass And Conversion Prob
Mole Conversion
Stoichemistry
Stoicheometry
Molar Conversion
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| Mole Conversion |
| Calculating the mass of the one Molecule |
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Mole ConversionsCalculating the Mass of One Molecule-------------------------------------------------------------------------------- When calculating the mass of one molecule, do the following: Calculate the molar mass of the substance Divide it by Avogadro's Number Make sure you have a periodic table and a calculator handy. -------------------------------------------------------------------------------- Example #1 - What is the mass of one molecule of H2O? Step #1 - the molar mass of water is 18.015 g/mol. This was calculated by multiplying the atomic weight of hydrogen (1.008) by two and adding the result to the weight for one oxygen (15.999). Please remember that you need the molar mass first when trying to find the mass of one molecule. Step #2 - divide the substance's molar mass by Avogadro's Number. 18.015 grams/mol ---------------------------- = 2.992 x 10¯23 grams 6.022 x 1023 mol¯1 Note that the final answer has been rounded to four significant figures (from 2.9915 - note use of rounding with five rule) and that the unit of mole cancels. -------------------------------------------------------------------------------- Example #2 - calculate the mass (in grams) of one molecule of CH3COOH The molar mass of CH3COOH is 60.06 g/mol. 60.06 g/mol -------------------------- = 9.973 x 10¯23 g 6.022 x 1023 mol¯1 -------------------------------------------------------------------------------- Practice Problems Calculate the mass (in grams) for one molecule of: 1) H2 2) PCl5 3) UF6 4) F2 5) CH4 ------------------------------- Answers1) H2 Step One: the molar mass of H2 is 2.016 g/mol Step Two: 2.016 g/mol -------------------------- = 3.348 x 10¯24 g 6.022 x 1023 mol¯1 -------------------------------------------------------------------------------- 2) PCl5 Step One: the molar mass of PCl5 is 208.239 g/mol Step Two: 208.239 g/mol -------------------------- = 3.458 x 10¯22 g 6.022 x 1023 mol¯1 -------------------------------------------------------------------------------- 3) UF6 Step One: the molar mass of UF6 is 352.019 g/mol Step Two 352.019 g/mol -------------------------- = 5.846 x 10¯22 g 6.022 x 1023 mol¯1 -------------------------------------------------------------------------------- 4) F2 Step One: the molar mass of F2 is 37.997 g/mol Step Two 37.997 g/mol -------------------------- = 6.310 x 10¯23 g 6.022 x 1023 mol¯1 -------------------------------------------------------------------------------- 5) CH4 Step One: the molar mass of CH4 is 16.043 g/mol Step Two 16.043 g/mol -------------------------- = 2.664 x 10¯23 g 6.022 x 1023 mol¯1 |
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