Weekly Solution Calculations 1. From a 95% ethanol (ETOH) stock solution, you make 250 ml of 70% ETOH. How much stock an

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Weekly Solution Calculations 1 From A 95 Ethanol Etoh Stock Solution You Make 250 Ml Of 70 Etoh How Much Stock An 1 (55.79 KiB) Viewed 25 times

Weekly Solution Calculations 1. From a 95% ethanol (ETOH) stock solution, you make 250 ml of 70% ETOH. How much stock and how much RO water do you need to make this solution? Show your work, include units. 2. Satisfied that you correctly calculated how much 95% ETOH to make 250 ml of 70% ETOH (on your calculation above. You add the 95% ETOH and bring the solution to volume. As you are labeling the bottle as 50% ETOH, you realize your mistake. Oops! You did not use a 250-ml volumetric flask. What is the actual concentration of the solution you just made? Show your work, include units. 3. You have a bacterial broth culture that contains 1 x 10" cells/ml. From this stock culture, you take 1.0 ml and add it to 9.0 ml of sterile broth. You label this tube 1. From tube 1, you take 0.1 ml of culture and add it to 9.9 ml of sterile broth. This is tube 2. From tube 2, you take 0.1 ml of culture and add it to 9.9 ml of sterile broth. This is tube 3. What is the concentration of cells in each of the three dilutions? Show your work. (Please note that cells/ml is a concentration ratio just like grams/ml, moles/L, etc. Cell concentration is termed cell density.)