to do T AaBbcer AaBbool AaBbccl AaBbccl AaBbcel AaBbcco AaB AaB bccD fast 1 Head

Question

to do T AaBbcer AaBbool AaBbccl AaBbccl AaBbcel AaBbcco AaB AaB bccD fast 1 Head 1 1 Heading 2 ing 3 1 Heading 4 1 Heading 5 1 Normal Title Subtitle Subtle Eppendort pipette Styles Chemicals Pure Cacos (provided, on the chemical shelf) 6 M HCl (provided, in the fume hood) 1000 ppm Mg2 stock solution (provided, by the centrifuge) unknown sample (give your labinstructor one 25-mL volumetric flask for unknown) Experimental Procedures A. Preparation of Ca2 Stock Solution weigh out accurately the quantity of Caco, required to make 100 ml of a 100 ppm Ca2. solution and deliver it into a 50 ml beaker. Add-20 ml of DI water to the beaker, and then add a minimum volume of 6 M HCl to dissolve the solid completely (add HCl drop by drop with glass rod stirring). Transfer all the solution to a 100 mL volumetric flask then rinse the beaker times with small portion of water and add the rinsings to the volumetric flask. Dilute the solution to the mark with DI H20. Note: 100 ppm ca solution is not the same as 100 ppm Cacos solution. B. Preparation of the Unknown

Explanation / Answer

One ppm is equal to the number of milligrams of solute dissolved per kg of solution.

since 1 mg = 10-3 g and 1 kg = 103 g. Assuming the density of water is 1.00 g/mL, 1 liter of solution = 1 kg and hence, 1 mg/L = 1 ppm.

or, 1mg/1000 ml = 1ppm

then, 1mg/100ml = 10 ppm and to make it 100ppm, multiply by 10 on both sides.

i.e., 10 mg/100ml = 100 ppm

Since, you weighed out 0.0250 g

0.0250 g in 1L = 0.025 ppm

You need to multiply it by 4000 to make it 100 ppm, now since you already have 0.025 g you can reduce the amount of water taken to make it 100 ppm.

i.e., 0.025g in 1000ml/4000 = 0.25 ml of water to make 100 ppm, since this way you cant get 100 ml of 100 ppm solution of Ca2+ for the reaction. You will have to weigh again to get 100ml of 100 ppm solution.

Take 10mg CaCO3 in 100 mL water to make 100 mL of 100 ppm Ca2+ solution.

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