SDSU Chemistry Placement Practice Test 2026 - Free Chemistry Placement Practice Questions and Study Guide

To determine how many moles are present in 50 grams of NaCl, we need to use the molar mass of sodium chloride (NaCl). The molar mass of NaCl is calculated by adding the atomic masses of sodium (Na) and chlorine (Cl). Sodium has an atomic mass of approximately 23 grams/mole, and chlorine has an atomic mass of about 35.5 grams/mole. Adding these together, the molar mass of NaCl is approximately 58.5 grams/mole.

Now, to find the number of moles in 50 grams of NaCl, we can use the formula:

\[

\text{moles of NaCl} = \frac{\text{mass of NaCl}}{\text{molar mass of NaCl}}

\]

Substituting the values we have:

\[

\text{moles of NaCl} = \frac{50 \text{ grams}}{58.5 \text{ grams/mole}} \approx 0.8547 \text{ moles}

\]

Upon re-evaluating the options given, the closest calculation for 50 grams gives approximately 0.8547 moles, which does not match the answer previously