1. **State the problem:** Calculate the grams and number of molecules for 7.50 moles of potassium chloride (KCl). 2. **Given data:** - Moles of KCl: $7.50$ mol - Molar mass of KCl: $74$ g/mol - Avogadro's number: $6.02 \times 10^{23}$ molecules/mol 3. **Formula used:** - To find grams: $$\text{grams} = \text{moles} \times \text{molar mass}$$ - To find molecules: $$\text{molecules} = \text{moles} \times 6.02 \times 10^{23}$$ 4. **Calculate grams:** $$7.50\ \text{mol} \times 74\ \frac{\text{g}}{\text{mol}} = 555\ \text{g}$$ 5. **Calculate molecules:** $$7.50\ \text{mol} \times 6.02 \times 10^{23}\ \frac{\text{molecules}}{\text{mol}} = 4.515 \times 10^{24}\ \text{molecules}$$ 6. **Final answers:** - Grams of KCl: $555$ g - Number of molecules: $4.515 \times 10^{24}$ molecules This means if you add 7.50 moles of potassium chloride, you are adding 555 grams and approximately $4.515 \times 10^{24}$ molecules of KCl.