Question

Be sure to answer all parts.

How many moles of pentane (C5H12) are contained in the following number of molecules? The answer should be provided in scientific notation.

a. 3.65 × 1023 molecules

× 10
(select)
mol

b. 2.62 × 1020 molecules

× 10
(select)
mol

Answer 1

a.) 6.06 x 10⁻¹ mol

b.) 4.35 x 10⁻⁴ mol

Step-by-step explanation:

To find the final answer, you need to use Avogadro's number to convert between molecules and moles. Remember to arrange the ratio/conversion in a way that allows for the cancellation of units. The answer should have 3 sig figs because the given values also have 3 sig figs.

Avogadro's Number:

6.022 x 10²³ molecules = 1 mole

a.)

3.65 x 10²³ molecules 1 mole
--------------------------------- x ------------------------------------ = 6.06 x 10⁻¹ mol
6.022 x 10²³ molecules

b.)

2.62 x 10²⁰ molecules 1 mole
-------------------------------- x --------------------------------------- = 4.35 x 10⁻⁴ mol
6.022 x 10²³ molecules