Atoms, Molecules, and Ions

In this set of practice problems, we will work on molar calculations such as converting between Mass, Moles, and Number of Ions and Atoms.

For all the problems, calculating the molar mass is not shown as it should be a relatively easy task using the periodic table. However, there is a separate article dedicated to this, so if you don’t feel comfortable with the concept of molar mass, please read it before working on these examples.

Other related topics are also covered in the following articles:

 

Practice

1.

Calculating Moles from Mass

Determine the number of moles in 59.7 grams of Al.

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2.

Determine the number of moles in 2.41 grams of FeO.

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3.

Calculate the number of moles in 0.647 grams of Al2O3.

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4.

Determine the number of moles in 3.56 grams of Mg(OH)2.

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5.

Determine the number of moles in 0.385 grams of N2O3.

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6.

Determine the number of moles in 165 grams of CaSO4.

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7.

Calculate the molar mass of N2O4 and determine how many moles of it are in a 23.9 g sample.

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8.

Calculate the number of moles in 165 grams of C3H6O.

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9.

Determine the number of moles in 452 grams of Co(NO3)3.

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10.

Calculating Mass from Moles 

Calculate the mass in grams of 0.598 moles of Fe.

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11.

Calculate the mass in grams of 0.168 moles of NO.

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12.

Calculate the mass in grams of 0.987 moles of (NH4)2S.

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13.

Calculate the mass in grams of 6.81 moles of Al2(SO4)3.

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14.

Calculate the mass in grams of 2.64 moles of methanol, CH3OH.

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15.

Calculate the mass in grams of 9.42 moles of NiCl2·6H2O.

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16.

Calculating the Number of Molecules from the Moles

How many molecules are there in a 0.487 mol sample of PCl5?

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17.

How many molecules (formula units) are there in a 5.84 mol sample of Na2SO3.

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18.

How many molecules of sucrose, C12H22O11 are there in a 0.684 mol sample?

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19.

Calculate the number of molecules in a 3.25-mol sample of propane, C3H8.

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20.

How many moles is 5.80 x 1025 molecules of POCl3?

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21.

Calculating the Number of Molecules from the Mass

How many molecules are there in a 5.12-g sample of K2O?

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22.

How many molecules of glucose, C6H12O6 are there in a 35.0 g sample?

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23.

Calculate the number of molecules of butane, C4H10, in its 2.40-gram sample.

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24.

How many Ethylene, C2H4 molecules are present in a 46.2 g sample? The molar mass of C2H4 is 28.1 g/mol.

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25.

Calculating the Number of Atoms

Calculate the number of atoms in a 2.56-g sample of Ca.

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26.

How many carbon atoms are there in a 0.590 mol sample of CCl4.

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27.

How many carbon atoms are there in a 0.964 mol sample of C2H6.

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28.

Which sample contains more Cl atoms: a) 1.25 moles of CH2Cl2 b) 2.15 moles of CH3Cl

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29.

The molecular formula of morphine is C17H19NO3. How many carbon atoms are in a 34.7-gram sample of morphine?

 

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30.

Isopropyl alcohol, also known as isopropanol, has found a widespread application in the preparation of pharmaceutical products. Answer the following questions considering that the molecular formula of isopropanol is C3H8O.

a) How many moles of C3H8O are contained in a 12.0 g sample of the alcohol?
b) How many molecules of C3H8O are contained in a 12.0 g sample of the alcohol?
c) How many atoms of oxygen are contained in a 12.0 g sample of the isopropyl alcohol (C3H8O)?
d) How many atoms of carbon are contained in a 12.0 g sample of the isopropyl alcohol (C3H8O)?

a)
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b)
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c)
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d)
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31.

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