Please help and show your work! 1) 25 ul of solute added to _______ ml of solven
ID: 196802 • Letter: P
Question
Please help and show your work!
1) 25 ul of solute added to _______ ml of solvent gives a 1:100 dilution.
2) You need to create a solution containing a total of 0.10 mg glucose. You have a stock solution of glucose at a concentration of 250 g/ml. How many ml of the stock solution do you need? _______________________
3). How many ml of 50X stock solution do you need to create 2 liters of 2X solution?
4. You are given a flask of unknown volume containing stinky apple juice. You remove 5 ml of this and mix it into 95 ml of sterile water. You repeat this procedure two more times. Finally you pipette (in duplicate) 0.1 ml of this final dilution onto agar plates, After 24 hours incubation, you find that 165 colonies have arisen on one plate and 180 have arisen on the other. What is the number of CFU/ml (colony forming units per ml) in the stinky apple juice?
Explanation / Answer
1) 25 ul of solute added to 2.475 ml of solvent gives a 1:100 dilution.
Dilution factor= aliquot volume/(aliquot volume + Diluent volume)
=25uL/(25uL + 2475uL)
=1/100
=1:100
3). How many ml of 50X stock solution do you need to create 2 liters of 2X solution?
Stock concentration= 50x
Required concentration= 2x
Required Volume= 2 L
C1V1=C2V2
(Stock) (required)
V1= C2V2/C1
V1= (2x x 2L)/50x = 0.08L
Take 80 mL of 50x stock solution and add 1920 mL water to get 2x solution,
4. You are given a flask of unknown volume containing stinky apple juice. You remove 5 ml of this and mix it into 95 ml of sterile water. You repeat this procedure two more times. Finally you pipette (in duplicate) 0.1 ml of this final dilution onto agar plates, After 24 hours incubation, you find that 165 colonies have arisen on one plate and 180 have arisen on the other. What is the number of CFU/ml (colony forming units per ml) in the stinky apple juice?
Answer:
Original CFU/ml = ?
Dilution factor = 5+95 mL = 1/20 times x 1/20 times x 1/20 times = 1/8000
Number of colonies= (165+180)/2 =172.5
Volume of sample =0.1 mL to the plate
cfu/ml = (no. of colonies)/( dilution factor x volume of culture plate)
cfu/ml = (172.5)/ (1/8000 x 0.1)
cfu/ml = 138 x 10^5 cfu/mL