Skip to main content
Chemistry LibreTexts

7.1.2: Practice Mole Calculations

  • Page ID
    236040
  • Molar Mass, Gram to Mole, Mole to Gram

    Exercise \(\PageIndex{1}\)

    How many moles of Ca3(PO4)2 are in 57.82 grams?

    Molar Mass

    Ca3(PO4)= \(\dfrac{310.18 g}{mol}\)

    Answer

    0.1864 moles

    How many grams of Zn(OH)2 are in 3.67 moles?

    Molar Mass

    Zn(OH)= \(\dfrac{99.41 g}{mol}\)

    Answer

    365 grams

    How many moles of Mg(NO3)2 are in 487.6 grams?

    Molar Mass

    Mg(NO3)= \(\dfrac{148.33 g}{mol}\)

    Answer

    3.287 moles

    Using Avogadro's Number

    Exercise \(\PageIndex{1}\)

    How many molecules of H2O are in 0.0643 grams of H2O?

    Answer

    0.0643 grams of H2O is equal to 0.00357 moles, which is 2.15 x 1021 molecules

    How many moles of Au is equal to 4.77 x 1027 Au atoms?

    Answer

    7920 moles

    Using Formula Subscripts

    Exercise \(\PageIndex{1}\)

    How many moles of NH3 would contain 8.18 moles of H atoms?

    Answer

    2.73 moles NH3

    How many Br atoms are in 0.453 moles of CBr4?

    Answer

    1.09 x 1024 Br atoms

    Mixed

    Exercise \(\PageIndex{1}\)

    How many moles of Ca(OH)2 are in 5.62 g of Ca(OH)2?  

    Answer

    0.0758 mol Ca(OH)2

    How many moles of O are in this amount?  

    Answer

    0.152 mol O

    How many individual atoms of O are in this amount?  

    Answer

    9.13 x 1022 O atoms

    Exercise \(\PageIndex{1}\)

    How many moles of C4H8O2 can be made with 18.5 mol C?

    Answer

    4.63 moles of C4H8O2

    Exercise \(\PageIndex{1}\)

    How many grams of C4H8O2 can be made with 2.86 x 1021 C atoms?  (Hint: how many moles of C is this?)

    Hint

    0.00475 mol C

    Answer

    0.00119 mol C4H8O2 which is 0.105 g C4H8O2

     

    • Was this article helpful?