Question
19. Review How do you calculate the molarity of a solution? 20. Compare How does the number of moles of solute before a dilution compare with the number of moles of solute after the dilution? 21. Identify What are two ways of expressing the concentration of a solution as a percent? 22. Calculate What is the molarity of a solution containing 400 g CuSO_(4) in 4.00 L of solution? 23. Colculate How many milliliters of a stock solu- tion of 2.00M KNO_(3) would you need to prepare 100.0 mL of 0.150M KNO_(3) 24. Calculate How many moles of solute are present in 50.0 mL of 0.20MKNO_(3) 25. Calculate What is the concentration, in percent (v/v) of a solution containing 50 mL of diethyl ether (C_(4)H_(10)O) in 2.5 L of solution? 26. Calculate What mass of K_(2)SO_(4) would you need to prepare 1500 g of 5.0% K_(2)SO_(4)(m/m) solution? IDEA THE MOLE AND QUANTIFYING MATTER 27. What information would you need in order to convert molarity to percent by volume?
Answer
4.5
(218 Votes)
Zoe
Master · Tutor for 5 years
Answer
19. Molarity is calculated by dividing the number of moles of solute by the volume of the solution in liters.20. The number of moles of solute remains the same before and after a dilution.21. The concentration of a solution can be expressed as a percent by mass (mass of solute / mass of solution * 100%) or percent by volume (volume of solute / volume of solution * 100%).22. The molarity of the solution is 2.506 moles / 4.00 L = 0.6265 M.23. You would need (0.150M * 100.0 mL) / 2.00M = 7.5 mL of the stock solution.24. There are 0.20M * 0.050 L = 0.01 moles of solute in the solution.25. The concentration of the solution is (50 mL / 2500 mL) * 100% = 2% (v/v).26. You would need (5.0% / 100%) * 1500 g = 75 g of
.27. To convert molarity to percent by volume, you would need to know the volume of the solute and the volume of the solution.
Explanation
## Step1: To calculate the molarity of a solution, you need to know the number of moles of solute and the volume of the solution in liters. The formula for molarity is:### **Molarity = Moles of solute / Volume of solution in liters**## Step2: The number of moles of solute before a dilution is equal to the number of moles of solute after the dilution. This is because dilution does not change the amount of solute, it only changes the volume of the solution.## Step3: There are two ways of expressing the concentration of a solution as a percent: percent by mass and percent by volume. Percent by mass is calculated as (mass of solute / mass of solution) * 100%. Percent by volume is calculated as (volume of solute / volume of solution) * 100%.## Step4: To calculate the molarity of a solution containing 400 g
in 4.00 L of solution, first convert the mass of
to moles. The molar mass of
is approximately 159.609 g/mol. Therefore, the number of moles of
is 400 g / 159.609 g/mol = 2.506 moles. Then, use the formula for molarity to find the molarity of the solution.## Step5: To prepare 100.0 mL of 0.150M
from a stock solution of 2.00M
, use the formula for dilution: M1V1 = M2V2. Here, M1 is the molarity of the stock solution, V1 is the volume of the stock solution needed, M2 is the molarity of the diluted solution, and V2 is the volume of the diluted solution.## Step6: To find the number of moles of solute in 50.0 mL of 0.20M
, use the formula for molarity. Convert the volume of the solution to liters and then multiply by the molarity.## Step7: To calculate the concentration of a solution in percent (v/v), use the formula (volume of solute / volume of solution) * 100%. ## Step8: To prepare 1500 g of 5.0%
solution, first calculate the mass of
needed using the formula for percent by mass: (mass of solute / mass of solution) * 100%.## Step9: To convert molarity to percent by volume, you would need to know the volume of the solute and the volume of the solution.