Question

question 5 (3 points)
you are asked to make 125 grams of a 7% antifungal cream using tolnaftate powder and eucerin cream. how many grams of tolnaftate powder are needed? round to the nearest hundredths (w/w).

Explanation:

Step1: Recall the formula for (w/w) percentage

The formula for weight - weight percentage is $\text{Percentage (w/w)}=\frac{\text{Weight of solute}}{\text{Weight of solution}}\times100$. We know the percentage is $7\%$ and the weight of the solution (the antifungal cream) is $125$ grams. We need to find the weight of the solute (tolnaftate powder). Let the weight of tolnaftate powder be $x$ grams.

Step2: Rearrange the formula to solve for $x$

From $\text{Percentage (w/w)}=\frac{\text{Weight of solute}}{\text{Weight of solution}}\times100$, we can rearrange it to $\text{Weight of solute}=\frac{\text{Percentage (w/w)}\times\text{Weight of solution}}{100}$. Substituting the given values: $\text{Percentage (w/w)} = 7$, $\text{Weight of solution}=125$ grams. So $x=\frac{7\times125}{100}$.

Step3: Calculate the value of $x$

First, calculate $7\times125 = 875$. Then, divide by $100$: $\frac{875}{100}=8.75$.

Answer:

$8.75$ grams