7.1.2: Practice Mole Calculations
- Page ID
- 424669
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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)2 = \(\dfrac{310.18 g}{mol}\)
- Answer
-
0.1864 moles
How many grams of Zn(OH)2 are in 3.67 moles?
- Molar Mass
-
Zn(OH)2 = \(\dfrac{99.41 g}{mol}\)
- Answer
-
365 grams
How many moles of Mg(NO3)2 are in 487.6 grams?
- Molar Mass
-
Mg(NO3)2 = \(\dfrac{148.33 g}{mol}\)
- 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