Question

question 1 (3 points)
a dermatologist prescribes drysol as a treatment for excessive underarm sweating.
drysol contains 15 g of aluminum chloride hexahydrate in 84 ml of an alcohol base.
what is the final strength of drysol? round to the nearest hundredths (w/v).
question 2 (3 points)
if 8 tablespoons of extract are mixed with distilled water to total 300 ml, what is the
final concentration (v/v)?

Explanation:

Question 1

Step1: Recall w/v formula

The weight/volume (w/v) percentage is calculated as $\frac{\text{mass of solute (g)}}{\text{volume of solution (mL)}} \times 100\%$. Here, the solute is aluminum chloride hexahydrate with mass $15\ \text{g}$, and the volume of the solution is $84\ \text{mL}$.

Step2: Apply the formula

Substitute the values into the formula: $\frac{15}{84} \times 100\%$. First, calculate $\frac{15}{84} \approx 0.17857$. Then multiply by $100\%$ to get $0.17857\times 100\% = 17.857\%$. Round to the nearest hundredths: $17.86\%$.

Step1: Convert tablespoons to mL (1 tablespoon ≈ 15 mL)

First, find the volume of the extract. Since 1 tablespoon is approximately 15 mL, for 8 tablespoons, the volume $V_{\text{extract}} = 8\times15 = 120\ \text{mL}$. The total volume of the solution is $300\ \text{mL}$.

Step2: Recall v/v formula

The volume/volume (v/v) percentage is $\frac{\text{volume of solute (mL)}}{\text{volume of solution (mL)}} \times 100\%$. Substitute the values: $\frac{120}{300} \times 100\%$.

Step3: Calculate the percentage

$\frac{120}{300}= 0.4$, then $0.4\times 100\% = 40\%$.

Answer:

$17.86\%$ (w/v)

Question 2