Question
1. What is the molecular mass of acetaldehyde, C2 H4 O? 2. How many moles of O2 molecules are in 48 g of O2 gas? How many moles of O atoms are in 48 g of O2 gas? 3. There are 1200 molecules in a sample. Write this quantity in scientific notation.
Answers
GPT-4o mini
1. To calculate the molecular mass of acetaldehyde (C₂H₄O), we add the atomic masses of all the atoms in the molecule:
- Carbon (C): There are 2 carbon atoms, with an atomic mass of about 12.01 g/mol.
- Hydrogen (H): There are 4 hydrogen atoms, with an atomic mass of about 1.01 g/mol.
- Oxygen (O): There is 1 oxygen atom, with an atomic mass of about 16.00 g/mol.
Now, we can calculate the molecular mass:
\[
\text{Molecular mass of C2H4O} = (2 \times 12.01) + (4 \times 1.01) + (1 \times 16.00)
\]
\[
= 24.02 + 4.04 + 16.00 = 44.06 \text{ g/mol}
\]
The molecular mass of acetaldehyde (C₂H₄O) is approximately **44.06 g/mol**.
2. To find the number of moles of O₂ gas in 48 g of O₂, we use the molar mass of O₂, which is approximately 32.00 g/mol (16.00 g/mol for each oxygen atom, and there are 2 in O₂):
\[
\text{Moles of O2} = \frac{\text{mass}}{\text{molar mass}} = \frac{48 \text{ g}}{32.00 \text{ g/mol}} = 1.5 \text{ moles of O2}
\]
Now, to find the number of moles of O atoms in 48 g of O₂, we note that each O₂ molecule contains 2 oxygen atoms. Therefore, the total number of moles of oxygen atoms is:
\[
\text{Moles of O atoms} = 2 \times \text{moles of O2} = 2 \times 1.5 = 3 \text{ moles of O atoms}
\]
So, in 48 g of O₂ gas, there are **1.5 moles of O₂ molecules** and **3 moles of O atoms**.
3. To express 1200 in scientific notation, we write it as follows:
\[
1200 = 1.2 \times 10^3
\]
Thus, the quantity of 1200 molecules in scientific notation is **\(1.2 \times 10^3\)**.
- Carbon (C): There are 2 carbon atoms, with an atomic mass of about 12.01 g/mol.
- Hydrogen (H): There are 4 hydrogen atoms, with an atomic mass of about 1.01 g/mol.
- Oxygen (O): There is 1 oxygen atom, with an atomic mass of about 16.00 g/mol.
Now, we can calculate the molecular mass:
\[
\text{Molecular mass of C2H4O} = (2 \times 12.01) + (4 \times 1.01) + (1 \times 16.00)
\]
\[
= 24.02 + 4.04 + 16.00 = 44.06 \text{ g/mol}
\]
The molecular mass of acetaldehyde (C₂H₄O) is approximately **44.06 g/mol**.
2. To find the number of moles of O₂ gas in 48 g of O₂, we use the molar mass of O₂, which is approximately 32.00 g/mol (16.00 g/mol for each oxygen atom, and there are 2 in O₂):
\[
\text{Moles of O2} = \frac{\text{mass}}{\text{molar mass}} = \frac{48 \text{ g}}{32.00 \text{ g/mol}} = 1.5 \text{ moles of O2}
\]
Now, to find the number of moles of O atoms in 48 g of O₂, we note that each O₂ molecule contains 2 oxygen atoms. Therefore, the total number of moles of oxygen atoms is:
\[
\text{Moles of O atoms} = 2 \times \text{moles of O2} = 2 \times 1.5 = 3 \text{ moles of O atoms}
\]
So, in 48 g of O₂ gas, there are **1.5 moles of O₂ molecules** and **3 moles of O atoms**.
3. To express 1200 in scientific notation, we write it as follows:
\[
1200 = 1.2 \times 10^3
\]
Thus, the quantity of 1200 molecules in scientific notation is **\(1.2 \times 10^3\)**.