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What volume of water should be added to 250cm3 of 1.0mhcl to prepare 0.25m? |
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Answer» Answer: Concentrated HCl is 12 M, which means 12 MOLES/L or 0.012 moles/mL. A 0.1 M solution of HCl has 0.1 moles/L. So for 1 liter of solution, you need 0.1 moles of HCl. To get 0.1 moles of HCl requires 8.33 mL con HCl: (0.012 moles/mL)(x mL) = 0.1 moles x = 0.1/0.012 = 8.33 But REMEMBER from above: This is for 1 L of solution, so you need to dilute that 8.33 mL of con HCL up to a total VOLUME of 1 liter (meaning you add the 8.33 mL con HCl to 991.67 mL water.) ALWAYS add acid to water, not the other way around - the dilution of HCl in water produces heat, and you want that heat to be dissipated over as much volume as possible. The phrase to remember is: “Add acid to wata, as you aughta.” |
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