Question

Serial dilution problem: Six test tubes are placed in a rack. To each tube add 4 mL of saline solution. Now to the first tube add 0.5 mL of concentrated protein (10 M) and mix well. Then transfer 1 mL of tube # 1 to tube # 2 and mix well. 1 mL of the contents of tube # 2 is then transferred to tube # 3, and the procedure is repeated for the remaining tubes. What is the dilution factor and molar concentration of protein in tube # 4? Show your answer by drawing 6 tubes and label them.

Answer 1

The dilution factor of protein in tube # 4 is 125. Molar concentration is 0.0088 M protein

Step-by-step explanation:

The dilution factor indicates how many times is more concentrated a main solution in relationship with a diluted solution. In this case, the main solution is in tube #1. For calculating the dilution factor and molar concentration in tube #4 we need the main solution concentration which comes from next equation:

Initial volume * initial concentration = final volume * final concentration

0.5 mL * 10M = 5mL * final concentration

1.1 M = final concentration = main solution concentration

Applying the same equation for remain tubes we have 0.22 M for tube #2, 0.044 M for tube # 4 and 0.0088 for tube # 4.

Dilution factor = Main solution concentration/tube 4 concentration

Dilution factor = 1.1/0.0088 = 125

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