Calculate the number of grams in 75 mL K2CrO4 (d=1.175 g/mL, 20% K2CrO4 by mass).
The correct answer and explanation is:
To calculate the number of grams in 75 mL of a 20% K₂CrO₄ solution, we can break it down into a few clear steps.
Step 1: Determine the mass of the solution
Given that the density (d) of the solution is 1.175 g/mL, we can find the total mass of the 75 mL solution using the formula: Mass of solution=Density×Volume\text{Mass of solution} = \text{Density} \times \text{Volume} Mass of solution=1.175 g/mL×75 mL\text{Mass of solution} = 1.175 \, \text{g/mL} \times 75 \, \text{mL} Mass of solution=88.125 g\text{Mass of solution} = 88.125 \, \text{g}
Step 2: Calculate the mass of K₂CrO₄ in the solution
The solution is 20% K₂CrO₄ by mass. To find the mass of K₂CrO₄ in the solution, we multiply the total mass of the solution by the percentage (converted to decimal form): Mass of K₂CrO₄=Mass of solution×Percentage of K₂CrO₄\text{Mass of K₂CrO₄} = \text{Mass of solution} \times \text{Percentage of K₂CrO₄} Mass of K₂CrO₄=88.125 g×0.20\text{Mass of K₂CrO₄} = 88.125 \, \text{g} \times 0.20 Mass of K₂CrO₄=17.625 g\text{Mass of K₂CrO₄} = 17.625 \, \text{g}
Final Answer:
The mass of K₂CrO₄ in 75 mL of the solution is 17.625 grams.
Explanation:
To summarize, we first used the density of the solution to find the total mass of 75 mL. Then, by using the concentration percentage of K₂CrO₄ (20% by mass), we calculated the mass of K₂CrO₄ in the solution. This method is commonly used for solutions where concentration is given by mass percentage.