# chemistry help help!!! plz help me. fast!! plzz?

1) What volume of a 5.00 mol/L stock solution is needed to make 2.00 L of a 0.125 mol/L solution? (1.5 marks)

2) Find the new concentration when 225 mL of a 3.00 mol/L solution has 575 mL of water added to it. (2 marks)

3)What volume of water must be added to 250.0 mL of a 0.650 mol/L calcium chloride solution to produce a 0.430 mol/L solution?

### 1 Answer

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- AshLv 71 month agoFavourite answer
1. C₁V₁ = C₂V₂

V₁ = C₂V₂/C₁ = (0.125 mol/L)(2.00 L)/(5.00 mol/L) = 0.05 L

2. C₁V₁ = C₂V₂

C₂ = C₁V₁/V₂ = (3.00 mol/L)(225 mL)/(225 mL + 575 mL) = 0.844 mol/L

3. C₁V₁ = C₂V₂

V₂ = C₁V₁/C₂ = (0.650 mol/L)(250.0 mL)/(0.430 mol/L) = 378 mL

Volume of water to be added = 378 mL - 250.0 mL = 128 mL

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