a. What is the molecular weight of aspirin (C9H8O4)?
180.1574 amu
b. What is the mass of 0.00785 mol of aspirin?
1.41 g
c. How many moles of aspirin are present in 100 mg of aspirin? Enter your answer in scientific notation.
5E-4 mol aspirin
d. How many molecules of aspirin are present in 5.00 g of aspirin? Enter your answer in scientific notation.
1.67E22 molecules aspirin
All of these are ok except for c. You don't have enough significant figures in c. You have 3 s.f. in 0.100 g; your answer should have 3 s.f. (I would buy 5.55E-4)
Here are the step-by-step calculations for each question:
a. To calculate the molecular weight of aspirin (C9H8O4), you need to sum up the atomic weights of all its constituent atoms.
- Atomic weight of carbon (C): 12.01 amu
- Atomic weight of hydrogen (H): 1.008 amu
- Atomic weight of oxygen (O): 16.00 amu
Now, calculate the molecular weight:
Molecular Weight of Aspirin = (9 * Atomic weight of carbon) + (8 * Atomic weight of hydrogen) + (4 * Atomic weight of oxygen)
= (9 * 12.01 amu) + (8 * 1.008 amu) + (4 * 16.00 amu)
= 180.1574 amu
Therefore, the molecular weight of aspirin is 180.1574 amu.
b. To calculate the mass of 0.00785 mol of aspirin, you can use the formula:
Mass = Moles * Molecular Weight
Mass of Aspirin = 0.00785 mol * 180.1574 g/mol
= 1.41 g
Therefore, the mass of 0.00785 mol of aspirin is 1.41 g.
c. To calculate the number of moles of aspirin present in 100 mg, you can use the formula:
Moles = Mass / Molecular Weight
Moles of Aspirin = 100 mg / 1,000 mg/g / 180.1574 g/mol
= 5E-4 mol aspirin
Therefore, there are 5E-4 mol of aspirin present in 100 mg.
d. To calculate the number of molecules of aspirin present in 5.00 g, you can use the formula:
Number of Molecules = (Mass * Avogadro's number) / Molecular Weight
Number of Molecules = (5.00 g * 6.022 x 10^23 molecules/mol) / 180.1574 g/mol
= 1.67E22 molecules aspirin
Therefore, there are 1.67E22 molecules of aspirin present in 5.00 g.
To find the molecular weight of aspirin (C9H8O4), you can use the periodic table to find the atomic weights of each element and then calculate the total molecular weight.
Here's how you can do it:
a. The molecular weight of aspirin (C9H8O4) is calculated by summing the atomic weights of carbon (C), hydrogen (H), and oxygen (O) atoms present in the molecule.
The atomic weight of carbon (C) = 12.01 amu
The atomic weight of hydrogen (H) = 1.008 amu
The atomic weight of oxygen (O) = 16.00 amu
Calculate the molecular weight:
(9 * atomic weight of carbon) + (8 * atomic weight of hydrogen) + (4 * atomic weight of oxygen) = 180.1574 amu
So, the molecular weight of aspirin is 180.1574 amu.
b. To find the mass of 0.00785 mol of aspirin, you need to use the molecular weight of aspirin calculated in part a.
Mass = number of moles * molecular weight
Mass = 0.00785 mol * 180.1574 amu
Converting amu to grams (1 amu = 1.66053906660 × 10^-24 grams):
Mass = 0.00785 mol * 180.1574 amu * (1.66053906660 × 10^-24 grams/amu) = 1.41 grams
So, the mass of 0.00785 mol of aspirin is 1.41 grams.
c. To find the number of moles of aspirin in 100 mg of aspirin, you can use the molecular weight of aspirin calculated in part a.
Mass = number of moles * molecular mass
Rearrange the equation to solve for the number of moles:
Number of moles = Mass / molecular mass
Number of moles = 100 mg / 180.1574 amu * (1 g / 1000 mg)
Number of moles = 0.1 g / 180.1574 amu
Converting grams to moles (1 g = 1/1000 kg = 6.02214076 × 10^23 amu):
Number of moles = 0.1 g / 180.1574 amu * (6.02214076 × 10^23 amu/mol) = 5E-4 mol
So, there are 5E-4 moles of aspirin in 100 mg of aspirin.
d. To find the number of molecules of aspirin in 5.00 g of aspirin, you need to use Avogadro's number (6.02214076 × 10^23 molecules/mol) and the molecular weight of aspirin calculated in part a.
Number of molecules = number of moles * Avogadro's number
Number of moles = Mass / molecular weight
Number of molecules = (mass of aspirin / molecular weight) * Avogadro's number
Number of molecules = (5.00 g / 180.1574 amu) * (6.02214076 × 10^23 amu/mol) = 1.67E22 molecules
So, there are 1.67E22 molecules of aspirin in 5.00 g of aspirin.