Question

1. if you have 158.2 grams of table salt, how many molecules do you have? (0.5 points) *

1.535 x 10^-20 molecules
4.567 x 10^25 molecules
1.630 x 10^24 molecules
5.567 x 10^27 molecules

1. how many moles are in 28 grams of carbon dioxide? (0.5 points) *

1.7 x 10^25 mol
4.7 x 10^-23 mol
3.8 x 10^23 mol
0.64 mol

Explanation:

Question 11

Step 1: Find molar mass of NaCl

Table salt is NaCl. Molar mass of Na is 22.99 g/mol, Cl is 35.45 g/mol. So molar mass \( M = 22.99 + 35.45 = 58.44 \) g/mol.

Step 2: Calculate moles of NaCl

Moles \( n = \frac{\text{mass}}{\text{molar mass}} = \frac{158.2\ \text{g}}{58.44\ \text{g/mol}} \approx 2.707\ \text{mol} \).

Step 3: Calculate number of molecules

Using Avogadro's number \( N_A = 6.022 \times 10^{23}\ \text{molecules/mol} \), number of molecules \( N = n \times N_A = 2.707\ \text{mol} \times 6.022 \times 10^{23}\ \text{molecules/mol} \approx 1.630 \times 10^{24}\ \text{molecules} \).

Step 1: Find molar mass of CO₂

Molar mass of C is 12.01 g/mol, O is 16.00 g/mol. So \( M = 12.01 + 2\times16.00 = 44.01 \) g/mol.

Step 2: Calculate moles of CO₂

Moles \( n = \frac{\text{mass}}{\text{molar mass}} = \frac{28\ \text{g}}{44.01\ \text{g/mol}} \approx 0.636\ \text{mol} \approx 0.64\ \text{mol} \).

Answer:

1.630 x 10^24 molecules

Question 12