Question

If you have

• 1 M Tris-HCl solution
• NaCl
• 100% Tween

How would you make 500 mL of 0.5 M NaCl, 0.1% Tween, and 100 mM Tris-HCl?

i suck at buffer questions.... please help !!!

Answer 1

make 500 mL of 0.5 M NaCl, 0.1% Tween, and 100 mM Tris-HCl , you have to take 14.61gram of NaCl, 0.5ml of Tween and 50ml of Tris HCl stock , mix them and make up volume up to 500ml

we have given

• 1 M Tris-HCl solution stock
• NaCl ( MW 58.44 g/mol )
• 100% Tween

we have to make

500 mL solution containing

0.5 M NaCl, 0.1% Tween, and 100 mM Tris-HCl

1. calculate amount of NaCl require to make 500ml of 0.5M NaCl solution

we know that 1M solution = gram molecular weight of substance in 1liter of solution

i.e. 1M NaCl solution means 58.44 gram of NaCl in 1 liter of water

but we have to make 500ml NaCl of 0.5M concentration

so that

if,

58.44 gram in 1000ml= 1M, then

58.44 x 0.5= 29.22gram in 500ml = 1M

But we want 0.5M NaCl solution so that

29.22 x 0.5= 14.61gram

To make 500ml of 0.5M solution we have to add 14.61 gram of NaCl in 500ml of water

2. 0.1% of tween

0.1% = 0.1 part out of 100 = 0.1ml in 100ml

But we have to make 500ml so that

To make 500ml of 0.1% tween we have to add 0.1 x 500/100 = 0.5 ml of tween in 500ml of solution

3. calculations for 100 mM Tris-HCl

We have stock of 1M= 1000mM= C1

Volume of stock needed= ?

Volume of solution =V2= 500ml

Concentration of solution = 100mM

We know the formula

C1V1=C2V2

V1=C2V2/C1

V1=500 x 100= 1000= 50000/1000= 50ml

We have to take 50ml of 1M Tris-HCl to make 500ml of 100mM solution