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Counting units are used for certain kinds of objects depending on their size. For example, eggs are counted in twelves, called dozens, and shoes are counted in pairs. Paper is counted in reams and pencils are counted in the gross. Chemists also need a unit for counting very small particles like molecules, formula units and atoms. This unit is called the mole. A mole is the SI base unit for measuring the amount of a substance. One mole is 6.02 * 10^23 particles. This number is called Avogadro's number, after Amedeo Avogadro. This quiz will cover the basics of counting small particles. You will need a calculator. Read the questions carefully and select the best answer from the choices.
How many atoms are in 2.5 moles of zinc?
1.51 * 10^24 atoms
3.51 * 10^24 atoms
6.02 * 10^24 atoms
6.02 * 10^23 atoms
How many formula units are in 3.25 moles of silver nitrate?
6.03 * 10^23 fmu
2.34 * 10^24 fmu
1.96 * 10^24 fmu
3.96 * 10^24 fmu
How many atoms are in four moles of hydrogen gas?
2.41* 10^24 atoms
0.41* 10^24 atoms
2.41* 10^23 atoms
1.21* 10^24 atoms
How many molecules are in 1.5 moles of water?
3.0 * 10^23 molecules
9.0 * 10^23 molecules
9.0 * 10^24 molecules
6.02 * 10^23 molecules
How many formula units are in 3.3 moles of NaCl?
2.49*10^24 fmu
1.87*10^24 fmu
1.459*10^24 fmu
1.99*10^24 fmu
Ethanol, CH3CH2OH, is known as grain alcohol and is the alcohol found in alcoholic beverages. Calculate the mole fraction of ethanol in a solution that contains 4.76 g of ethanol dissolved in 50.0 g of water.
3.03590
0.23230
0.03590
0.45590
True or False, One mole is 6.02 * 10^23 particles. This number is called Avogadro's number, after Amedeo Avogadro.
False
True
How many moles are 2.85 x 1018 atoms of iron?
4.72 x 10^-6 moles
4.73 x 10^-6 moles
1.72 x 10^-6 moles
4.73 x 10^6 moles
