Multiple Choice
How many grams of hydrazine, N2H4, must be added to a solvent to prepare 204 mL of a solution that is 0.42 M hydrazine?
6. Chemical Quantities & Aqueous Reactions
Molarity
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How many moles of CaCl2 are present in 250 mL of a 3.0 M CaCl2 solution?
A
0.75 moles
B
3.0 moles
C
0.25 moles
D
1.5 moles
Verified step by step guidance1
Understand that molarity (M) is defined as moles of solute per liter of solution. Therefore, a 3.0 M CaCl2 solution means there are 3.0 moles of CaCl2 in every 1 liter of solution.
Convert the volume of the solution from milliliters to liters. Since there are 1000 milliliters in a liter, divide 250 mL by 1000 to convert it to liters.
Use the formula for molarity: \( M = \frac{\text{moles of solute}}{\text{liters of solution}} \). Rearrange this formula to solve for moles of solute: \( \text{moles of solute} = M \times \text{liters of solution} \).
Substitute the given values into the rearranged formula: \( \text{moles of CaCl2} = 3.0 \text{ M} \times 0.250 \text{ L} \).
Calculate the product to find the number of moles of CaCl2 present in the solution.
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