pre lab question: 1. In the first part of this experiment, you are going to make
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Question
pre lab question:
1. In the first part of this experiment, you are going to make a solution of calcium chloride. Describe how you are going to do this. Try to keep this to about 6 sentences or less.
2. To make your solution of calcium chloride, you will have to take some calcium chloride salt from a stock bottle and dissolve it. How will you know how much salt to take?
3. In the second part of this experiment, you are gong to take the measurements needed to determine the density of your calcium chloride solution. Describe how you are going to do this.
4. By the time you’re done with lab, you will have density and concentration data for several CaCL2 solutions. Describe what you’re going to do these.
Explanation / Answer
Suppose you want to make a 1M solution of CaCl2 having a volume of 200 mL.
Since molarity=moles/volume
So,
Moles = molarity*volume = 1*0.2 = 0.2 moles
So you need 0.2 moles of CaCl2 and 200 mL distilled water(DW).
MW of CaCl2 is 111g
So, mass of CaCl2 required = 0.2*111 = 22.2 g
So, weigh out 22.2 g of CaCl2 and dissolve in 200 mL DW to make a solution of 1M CaCl2.
Next, you need to check the density.
Density=Mass/Volume
Volume of solution = 200 mL
Mass of this 200mL solution has to be measured. Once you measure the mass (say 'x' grams), use the formula:
Density, d = Solution Mass/Solution volume = x/200 g/mL
This is how you calculate the concentration and density.
Using several data values for the density and concentration, we can average out a single value for density and for concentration.
The following relation holds between the density and concentration:
Concentration = moles/Volume = (Mass/MW)/volume = (Mass/111)/volume = Density/111
Here, 111g is the MW of CaCl2.
Let me know what else you need to know.
Hope this helps !
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