Some water evaporated from a stock solution that was left open for several days. How will the concentration of the solution change?

A. It will increase.
Correct!

B. It will decrease.
Incorrect. Concentration is the ratio of moles of solute to liters of the solution. Water evaporating changes the liters of solution, but it doesn’t change the amount of moles. Therefore, there will be the same amount of moles dissolved in less solution, creating a more concentrated solution.

C. It will not change.
Incorrect. Concentration is the ratio of moles of solute to liters of the solution. Water evaporating changes the liters of solution, but it doesn’t change the amount of moles. Therefore, there will be the same amount of moles dissolved in less solution, creating a more concentrated solution.

D. There's not enough information to know.
Incorrect. Concentration is the ratio of moles of solute to liters of the solution. Water evaporating changes the liters of solution, but it doesn’t change the amount of moles. Therefore, there will be the same amount of moles dissolved in less solution, creating a more concentrated solution.

A student dilutes 0.10L of a 6.0 M HCl solution to form 250 mL of a new solution. What is the concentration of the new solution?

A. 2.4 M
Correct!

B. 0.0024 M
Incorrect. Remember to use the formula M1V1 = M2V2. Also, remember to convert 250 mL into L. The equation should be (0.10L) × (6.0M) = (0.250L) × M.

C. 15 M
Incorrect. Remember to use the formula M₁V₁ = M₂V₂. Also, remember to convert 250 mL into L. The equation should be (0.10L) x (6.0M) = (0.250L) × M.

D. 0.15
Incorrect. Remember to use the formula M₁V₁ = M₂V₂. Also, remember to convert 250 mL into L. The equation should be (0.10L) × (6.0M) = (0.250L) × M.

How much of a concentrated 3.0M CuSO₄ solution is needed to make 500 mL of a 0.50 M CuSO₄ solution?

A. 750 mL
Incorrect. To solve the problem, convert 500 mL to L, then substitute into the equation M₁V₁ = M₂V₂. The equation should be (3.0M) × V1 = (0.50M) × (0.500L).

B. 16.7
Incorrect. To solve the problem, convert 500 mL to L, then substitute into the equation M₁V₁ = M₂V₂. The equation should be (3.0M) × V1 = (0.50M) × (0.500L).

C. 3.00 mL
Incorrect. To solve the problem, convert 500 mL to L, then substitute into the equation M₁V₁ = M₂V₂. The equation should be (3.0M) × V1 = (0.50M) × (0.500L).

D. 83.3 mL
Correct!

How much water needs to be added to 30 mL of a 6.0 M HCl solution to make a 0.5 M HCl solution?

A. 360 mL
Incorrect. The total volume of the diluted solution will be 360 mL. To determine the amount of water that needs to be added, subtract the amount of concentrated solute that is already in the container. Use equation 360mL – 30mL = 330mL.

B. 330 mL
Correct!

C. 60 mL
Incorrect. To solve the problem, first calculate the total volume of the dilute solution using M₁V₁ = M₂V₂. The total volume of the diluted solution will be 360 mL. To determine the amount of water that needs to be added, subtract the amount of concentrated solute that is already in the container. Use equation 360mL – 30mL = 330mL.

D. 0.1 mL
Incorrect. To solve the problem, first calculate the total volume of the dilute solution using M₁V₁ = M₂V₂. The total volume of the diluted solution will be 360 mL. To determine the amount of water that needs to be added, subtract the amount of concentrated solute that is already in the container. Use equation 360mL – 30mL = 330mL.