Question

1. $\frac{3.01 \times 10^{23}}{6.02 \times 10^{23}}$ atoms ni = 0.500
2. $\frac{1000. \text{atoms al}}{6.02 \times 10^{23}}$ =

convert to number of atoms

1. 3.00 moles ar
2. 8.50 moles fe
3. 25.0 moles ar
4. 0.00100 mole na
5. 540 grams al
6. 294 grams au
7. 6.35 grams cu
8. 1.00 grams li

Explanation:

Step1: Recall Avogadro's number: $N_A = 6.02 \times 10^{23} \text{ atoms/mol}$

Moles to atoms: $\text{Atoms} = n \times N_A$
Grams to atoms: $\text{Atoms} = \frac{m}{M} \times N_A$, where $M$ is molar mass.

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Q16: Calculate moles of Al

Step1: Define given values

$\text{Atoms Al} = 1000$, $N_A = 6.02 \times 10^{23} \text{ atoms/mol}$

Step2: Moles = atoms / $N_A$

$n = \frac{1000}{6.02 \times 10^{23}} = 1.66 \times 10^{-21} \text{ mol}$

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Q17: Convert moles Ar to atoms

Step1: Define given values

$n = 3.00 \text{ mol}$, $N_A = 6.02 \times 10^{23} \text{ atoms/mol}$

Step2: Atoms = moles × $N_A$

$\text{Atoms} = 3.00 \times 6.02 \times 10^{23} = 1.81 \times 10^{24}$

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Q18: Convert moles Fe to atoms

Step1: Define given values

$n = 8.50 \text{ mol}$, $N_A = 6.02 \times 10^{23} \text{ atoms/mol}$

Step2: Atoms = moles × $N_A$

$\text{Atoms} = 8.50 \times 6.02 \times 10^{23} = 5.12 \times 10^{24}$

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Q19: Convert moles Ar to atoms

Step1: Define given values

$n = 25.0 \text{ mol}$, $N_A = 6.02 \times 10^{23} \text{ atoms/mol}$

Step2: Atoms = moles × $N_A$

$\text{Atoms} = 25.0 \times 6.02 \times 10^{23} = 1.51 \times 10^{25}$

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Q20: Convert moles Na to atoms

Step1: Define given values

$n = 0.00100 \text{ mol}$, $N_A = 6.02 \times 10^{23} \text{ atoms/mol}$

Step2: Atoms = moles × $N_A$

$\text{Atoms} = 0.00100 \times 6.02 \times 10^{23} = 6.02 \times 10^{20}$

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Q21: Convert grams Al to atoms

Step1: Define values: $m=540\text{g}$, $M_{\text{Al}}=27.0\text{g/mol}$

Step2: Calculate moles of Al

$n = \frac{540}{27.0} = 20.0 \text{ mol}$

Step3: Atoms = moles × $N_A$

$\text{Atoms} = 20.0 \times 6.02 \times 10^{23} = 1.20 \times 10^{25}$

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Q22: Convert grams Au to atoms

Step1: Define values: $m=294\text{g}$, $M_{\text{Au}}=197\text{g/mol}$

Step2: Calculate moles of Au

$n = \frac{294}{197} \approx 1.49 \text{ mol}$

Step3: Atoms = moles × $N_A$

$\text{Atoms} = 1.49 \times 6.02 \times 10^{23} \approx 8.97 \times 10^{23}$

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Q23: Convert grams Cu to atoms

Step1: Define values: $m=6.35\text{g}$, $M_{\text{Cu}}=63.5\text{g/mol}$

Step2: Calculate moles of Cu

$n = \frac{6.35}{63.5} = 0.100 \text{ mol}$

Step3: Atoms = moles × $N_A$

$\text{Atoms} = 0.100 \times 6.02 \times 10^{23} = 6.02 \times 10^{22}$

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Q24: Convert grams Li to atoms

Step1: Define values: $m=1.00\text{g}$, $M_{\text{Li}}=6.94\text{g/mol}$

Step2: Calculate moles of Li

$n = \frac{1.00}{6.94} \approx 0.144 \text{ mol}$

Step3: Atoms = moles × $N_A$

$\text{Atoms} = 0.144 \times 6.02 \times 10^{23} \approx 8.67 \times 10^{22}$

Answer:

1. $1.66 \times 10^{-21} \text{ mol Al}$
2. $1.81 \times 10^{24} \text{ atoms Ar}$
3. $5.12 \times 10^{24} \text{ atoms Fe}$
4. $1.51 \times 10^{25} \text{ atoms Ar}$
5. $6.02 \times 10^{20} \text{ atoms Na}$
6. $1.20 \times 10^{25} \text{ atoms Al}$
7. $8.97 \times 10^{23} \text{ atoms Au}$
8. $6.02 \times 10^{22} \text{ atoms Cu}$
9. $8.67 \times 10^{22} \text{ atoms Li}$