How many grams of KCl are needed to prepare 0.5 moles of KCl solution?

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Question: How many grams of KCl are needed to prepare 0.5 moles of KCl solution?

Options:

Correct Answer: 74.5 g

Solution:

The molar mass of KCl is 39 g/mol (K) + 35.5 g/mol (Cl) = 74.5 g/mol. Therefore, 0.5 moles of KCl will weigh 0.5 x 74.5 g = 37.25 g.

How many grams of KCl are needed to prepare 0.5 moles of KCl solution?

How many grams of KCl are needed to prepare 0.5 moles of KCl solution?

Step 1: Find the molar mass of KCl by adding the atomic masses of potassium (K) and chlorine (Cl).
Step 2: The atomic mass of potassium (K) is 39 g/mol.
Step 3: The atomic mass of chlorine (Cl) is 35.5 g/mol.
Step 4: Add the atomic masses together: 39 g/mol + 35.5 g/mol = 74.5 g/mol.
Step 5: To find the weight of 0.5 moles of KCl, multiply the number of moles (0.5) by the molar mass (74.5 g/mol).
Step 6: Calculate: 0.5 x 74.5 g = 37.25 g.
Step 7: Therefore, you need 37.25 grams of KCl to prepare 0.5 moles of KCl solution.

Molar Mass Calculation – Understanding how to calculate the molar mass of a compound by summing the atomic masses of its constituent elements.
Mole Concept – Applying the mole concept to convert between moles and grams using the molar mass.