Multiple Choice
How many grams of sucrose (C₁₂H₂₂O₁₁) are in 1.55 L of 0.758 M sucrose solution?
6. Chemical Quantities & Aqueous Reactions
Molarity
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How many moles of K⁺ are present in 343 mL of a 1.27 M solution of K₃PO₄?
A
0.435 moles
B
1.31 moles
C
0.872 moles
D
0.145 moles
Verified step by step guidance1
Start by understanding the concept of molarity, which is defined as the number of moles of solute per liter of solution. The formula for molarity is \( M = \frac{n}{V} \), where \( M \) is the molarity, \( n \) is the number of moles, and \( V \) is the volume in liters.
Convert the volume from milliliters to liters. Since there are 1000 milliliters in a liter, divide 343 mL by 1000 to get the volume in liters: \( V = \frac{343}{1000} \text{ L} \).
Use the molarity formula to find the number of moles of \( K_3PO_4 \) in the solution. Substitute the given molarity (1.27 M) and the converted volume (in liters) into the formula: \( n = M \times V \).
Recognize that each formula unit of \( K_3PO_4 \) contains 3 moles of \( K^+ \) ions. Therefore, multiply the moles of \( K_3PO_4 \) by 3 to find the total moles of \( K^+ \) ions: \( n_{K^+} = 3 \times n_{K_3PO_4} \).
Review the calculation steps to ensure accuracy and consistency with the units and conversion factors used throughout the problem.
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