Research and Calculations:
How many water (H2O) molecules are in a single snowflake?
In order to answer this question, I first had to determine the mass of a single snowflake. While every snowflake is different and the mass can very widely, I found that on average a single snowflake has a mass of about 0.003 grams. Assuming that a snowflake is made up entirely of water (H2O), this would mean that there are 0.003 grams of H2O in one snowflake. Using this information, I created the following conversion factor:
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Next, I had to find the molar mass of water (H2O). According to the periodic table, hydrogen (H) has an average atomic mass of 1.00794 amu, and oxygen (O) has an average atomic mass of 15.9994 amu. Since there are two hydrogen atoms and one oxygen atom in each H2O molecule, I made the calculation 1.00794(2)+15.9994=18.01528 to find the molecular mass, which is the mass of one molecule of H2O. The molecular mass (measured in atomic mass units [amu]) is equal to the molar mass (measured in grams per mole [g/mol]) so by converting from atomic mass units to grams, we have the molar mass of H2O, which is 18.01528 grams per mole. Using this information, I created the following conversion factor:
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Finally, I had to convert from the number of moles to molecules in order find the answer to my research question. To do this, I used Avogadro's number, 6.022*10^23, which is defined as the number of units (particles, molecules, atoms, ions, etc.) in one mole of any substance. In this case, there are 6.022*10^23 molecules of H2O in 1 mole of H2O, as represented by the following conversion factor:
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To find the final answer to my research question, the number of water (H2O) molecules in a single snowflake, I multiplied all of my conversion factors together. All of the unnecessary units canceled out and left the final answer, as shown in the calculations below:
There are 1.8066*10^21 molecules of water (H2O) in a single snowflake.
There are 1.8066*10^21 molecules of water (H2O) in a single snowflake.