Question 21 (2 points)

Question

The molar mass of water is 18.0 grams/mol. How many molecules are in 72.0 grams of water?





If you are unsure how to convert grams to particles, please see the example problem linked HERE.

a
3.13 x 1025 molecules

b
1.51 x 1023 molecules

c
2.41 x 1024 molecules

d
7.80 x 1026 molecules

Answer 1

To find the number of molecules in 72.0 grams of water, follow these steps:

1. Determine the number of moles of water in 72.0 grams using the molar mass of water (18.0 g/mol):

72.0 grams / 18.0 g/mol = 4 moles

2. Use Avogadro's number (6.022 x 10^23 molecules/mol) to convert moles to molecules:

4 moles x 6.022 x 10^23 molecules/mol = 2.41 x 10^24 molecules

Therefore, the answer is c) 2.41 x 10^24 molecules.