Video Transcript
What is the mass of 0.443 moles of
hydrazine, N2H4? Give your answer to one decimal
place. The molar mass of hydrogen is one
gram per mole, and the molar mass of nitrogen is 14 grams per mole.
In this question, we’ve been given
an amount of hydrazine in moles. Then, we need to calculate its
mass. We can relate the amount of a
substance to its mass using the equation 𝑛 equals lowercase 𝑚 divided by capital
𝑀. In this equation, 𝑛 represents the
amount of substance in moles. Lowercase 𝑚 represents the mass in
grams. Capital 𝑀 represents the molar
mass in grams per mole. The question provides us with the
amount, and we know we’re solving for the mass. But we aren’t given the molar
mass. So we’ll need to calculate it
first.
In the question, we are given the
molar masses of hydrogen and nitrogen. To calculate the molar mass of
hydrazine, we simply need to sum the average molar masses of the constituent
atoms. We’ll multiply the molar mass of
nitrogen by two and the molar mass of hydrogen by four, since there are two nitrogen
atoms and four hydrogen atoms in a molecule of hydrazine. We can now substitute the molar
masses of hydrogen and nitrogen into the equation. Performing the calculation, we find
that the molar mass of hydrazine is 32 grams per mole.
Now we can substitute the amount in
moles and the molar mass in grams per mole into the equation and solve for the
mass. We multiply both sides of the
equation by 32 grams per mole to isolate 𝑚. The mole units will cancel, leaving
us with the unit grams. Performing the calculation, we find
that the mass is 14.176 grams. Lastly, we need to round our answer
to one decimal place.
In conclusion, we have determined
that the mass of 0.443 moles of hydrazine is 14.2 grams.
