Unit 6-Review The Mole

Front

What is an empirical formula?

Back

An empirical formula represents the simplest whole-number ratio of atoms of each element in a compound. For example, the empirical formula of glucose (C6H12O6) is CH2O.

Front

Which of the following is not an empirical formula: H2O, NaCl, FeCl2, C2H4?

Back

C2H4 is not an empirical formula because it can be simplified to CH2.

Front

How do you calculate the number of moles from atoms?

Back

To calculate the number of moles from atoms, use the formula: Number of moles = Number of atoms × (1 mole / 6.022 x 10^23 atoms).

Front

What is the volume of one mole of gas at STP?

Back

One mole of gas occupies 22.4 liters at standard temperature and pressure (STP).

Front

How many moles are in 250 liters of N2 gas at STP?

Back

To find the number of moles, divide the volume by the volume of one mole: 250 L ÷ 22.4 L/mole = 11.16 moles.

Front

What is the relationship between moles and molecules?

Back

The number of molecules can be calculated using the formula: Number of molecules = Number of moles × 6.022 x 10^23 molecules/mole.

Front

How many molecules are in 5.9 moles of NaCl?

Back

To find the number of molecules, multiply: 5.9 moles × 6.022 x 10^23 molecules/mole = 3.6 x 10^24 molecules.

Front

What is the definition of a mole in chemistry?

Back

A mole is a unit of measurement that represents 6.022 x 10^23 particles (atoms, molecules, ions, etc.) of a substance.

Front

What is the difference between empirical and molecular formulas?

Back

An empirical formula shows the simplest ratio of elements in a compound, while a molecular formula shows the actual number of atoms of each element in a molecule.

Front

Which of the following is an empirical formula: H2O2, C2H6O12, CaCl2, N2O8?

Back

CaCl2 is an empirical formula because it cannot be simplified further.