Concentrated hydrochloric acid is a 38% solution of HCL in water and has a density of 1.18g/ml. How many milliliters of concentrated hydrochloric acid are needed to prepare 500ml of 1:200 HCL solution? The answer is not 2.12ml
My calculation:
1.18g/ml x 1000ml x 0.38/36.5 = 12.28M
500ml x 1:200 = 2.5
12.28/2.5 = 4.9ml
Who helps me to solve it for me. Tell me the right answer. Please help
Sometimes biochemists (I assume you are in a bio class) use funny symbols and nomenclature (at least in my opinion). Here is a web site that will explain some about dilutions.
http://www.stolaf.edu/people/muth/Appendix%20II.pdf
If I read this correctly, 1:200 means you want 1 mL stock solution diluted to 200 mL total volume or 0.005. So if you want 500 mL instead of 200 mL, that will be 2.5 mL diluted to 500 total volume. From the way your problem is stated I don't know if that is 1:200 of the 12.28 M stuff OR if it means 1:200 of something else. My best guess is that it means you take 2.5 mL of the 12.28 M concd HCl and dilute to 500 mL.
All of that means the density, %HCl etc etc are just extraneous data. Of course I may have interpreted the problem incorrectly.
To solve this problem, you need to calculate the volume of concentrated hydrochloric acid (HCl) that is needed to prepare the desired 500 ml of 1:200 HCl solution.
First, let's determine the concentration of the concentrated hydrochloric acid solution. It is given that the solution is 38% HCl, which means that for every 100 ml of solution, 38 ml is HCl. This can be written as a ratio of 38:100 or simplified to 19:50.
Next, you can calculate the volume of HCl needed for the 500 ml of 1:200 HCl solution. In a 1:200 HCl solution, there is 1 part HCl to 200 parts total solution. Since the total volume is 500 ml, you can calculate the volume of HCl as follows:
(1/201) x 500 ml = 2.487562 ml (approximately)
The volume of HCl required is approximately 2.49 ml, which differs from the answer you provided (4.9 ml). It's important to note that the calculation may differ based on how you interpreted the ratio and the units used. Ensure that you are using the correct ratios and units throughout the calculation.
Therefore, the right answer is approximately 2.49 ml of concentrated hydrochloric acid.