Make 1 ml of a 0.25nM solution of NaOH. (FW: 40). You are given a maximum of 2 g

Question

Make 1 ml of a 0.25nM solution of NaOH. (FW: 40). You are given a maximum of 2 g of NaOH as your starting material. (Remember that you need to consider the equipment available in the lab). Make 500 ml of a 50 X solution of PBS. Use this (50X PBS Buffer) to make 1 liter of 0.5X PBS solution. Write out how you would do this and include the concentration of each ingredient in the 0.5X Buffer. RECIPE FOR IX PBS 137 mM NaCl 10 mM Na_2HPO_4 2.7 mM KCl 2 mM KH2PO4 pH of 7.4. Write out the calculations and provide instructions on how to prepare a 7.5 % (Na_2CO_3) in 0.75M NaOH. Remember NaOH is caustic so make sure to include appropriate precautions.

Explanation / Answer

1. 2 L of 1x TE buffer.

So 10mM = 121.1 x (10 x 10-3 M) / 1 = 1.21 g

So if u dissolve 1.21g in 1L it will be 10mM.

So dissolve 2.42g in 2L = 10mM.

SO 1mM = 0.372g in 1000mL

So 0.744 g in 2000mL = 1mM

Dissolve these two ingradients in the above calculated amount.

2. 1mL of 0.25nM solution of NaOH.

Fw = 40. So 40g in 1000mL = 1M

Since we have 2g of NaOH , that is equal to 2g – 1000mL = 0.05M = 50mM

2g – 10mL =5M

1g – 10mL = 2.5 M

Prepare this solution and keep diluting 1:10

2.5M à0.25Mà0.025M(25mM)à2.5mMà0.25mMà0.025mM(25µM)à2.5µMà0.25 µMà0.025 µM(25nM)à 2.5nMà0.25nM.

  

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