Answer :
Sure! Let's break down the questions step by step.
Question 3: Which of the following statements is true about the Avogadro constant?
To identify the true statement regarding the Avogadro constant, let's understand what it represents. The Avogadro constant is a fundamental physical constant that describes the number of atoms, molecules, or particles in one mole of a substance. This constant is approximately [tex]\(6.02 \times 10^{23}\)[/tex].
- [A] states it is the number of grams of any element which contains [tex]\(6.02 \times 10^{23}\)[/tex] atoms of that element. This is incorrect because the Avogadro constant is about the number of atoms, not grams.
- [B] states it is the number of atoms contained in one mole of any element. This is correct because the Avogadro constant defines the number of atoms in a mole.
- [C] also states it is the number of atoms contained in one mole of any monatomic element. This is technically correct for monatomic elements as well, but [B] is more general.
- [D] states it is the number of particles (atoms, molecules, or ions) required to make one gram of a substance. This is not accurate because the Avogadro constant is related to moles, not grams.
The true statement is: [B] atoms contained in one mole of any element.
Question 4: If 1.00 g of an unknown molecular compound contains [tex]\(4.55 \times 10^{21}\)[/tex] molecules, what is its molar mass?
To find the molar mass of the compound, follow these steps:
1. Calculate the moles of molecules in the sample:
The number of molecules present is [tex]\(4.55 \times 10^{21}\)[/tex].
2. Use Avogadro constant:
The Avogadro constant is [tex]\(6.02 \times 10^{23}\)[/tex] molecules per mole.
[tex]\[
\text{Moles of molecules in sample} = \frac{\text{Number of molecules}}{\text{Avogadro constant}} = \frac{4.55 \times 10^{21}}{6.02 \times 10^{23}} \approx 0.00756 \text{ moles}
\][/tex]
3. Calculate the molar mass:
The sample mass is 1.00 g. Molar mass is calculated by dividing the mass of the sample by the number of moles of molecules.
[tex]\[
\text{Molar mass} = \frac{\text{Sample mass}}{\text{Moles of molecules in sample}} = \frac{1.00 \, \text{g}}{0.00756 \text{ moles}} \approx 132.31 \, \text{g/mol}
\][/tex]
The calculated molar mass is closest to: [E] 132 g/mol.
Question 3: Which of the following statements is true about the Avogadro constant?
To identify the true statement regarding the Avogadro constant, let's understand what it represents. The Avogadro constant is a fundamental physical constant that describes the number of atoms, molecules, or particles in one mole of a substance. This constant is approximately [tex]\(6.02 \times 10^{23}\)[/tex].
- [A] states it is the number of grams of any element which contains [tex]\(6.02 \times 10^{23}\)[/tex] atoms of that element. This is incorrect because the Avogadro constant is about the number of atoms, not grams.
- [B] states it is the number of atoms contained in one mole of any element. This is correct because the Avogadro constant defines the number of atoms in a mole.
- [C] also states it is the number of atoms contained in one mole of any monatomic element. This is technically correct for monatomic elements as well, but [B] is more general.
- [D] states it is the number of particles (atoms, molecules, or ions) required to make one gram of a substance. This is not accurate because the Avogadro constant is related to moles, not grams.
The true statement is: [B] atoms contained in one mole of any element.
Question 4: If 1.00 g of an unknown molecular compound contains [tex]\(4.55 \times 10^{21}\)[/tex] molecules, what is its molar mass?
To find the molar mass of the compound, follow these steps:
1. Calculate the moles of molecules in the sample:
The number of molecules present is [tex]\(4.55 \times 10^{21}\)[/tex].
2. Use Avogadro constant:
The Avogadro constant is [tex]\(6.02 \times 10^{23}\)[/tex] molecules per mole.
[tex]\[
\text{Moles of molecules in sample} = \frac{\text{Number of molecules}}{\text{Avogadro constant}} = \frac{4.55 \times 10^{21}}{6.02 \times 10^{23}} \approx 0.00756 \text{ moles}
\][/tex]
3. Calculate the molar mass:
The sample mass is 1.00 g. Molar mass is calculated by dividing the mass of the sample by the number of moles of molecules.
[tex]\[
\text{Molar mass} = \frac{\text{Sample mass}}{\text{Moles of molecules in sample}} = \frac{1.00 \, \text{g}}{0.00756 \text{ moles}} \approx 132.31 \, \text{g/mol}
\][/tex]
The calculated molar mass is closest to: [E] 132 g/mol.
