Question

We have a solution of protein that has a concentration of 0.25 mg/ml.

a.We need 20 g of the protein for an experiment. What volume of the protein solution do we need?

b.Suppose we want a solution containing 150 g of the protein at a concentration of 0.50 mg/ml. To do this we will first evaporate the liquid from enough of the protein solution to get 150 g. How much solution do we need to start with? How much H₂O do we add to get the desired concentration?

d.Suppose we want 1 ml of a 10 g/ml solution. How much H₂O and protein stock must we add to get this?

e.Suppose we want 100 l of a 0.1 g/l solution. How much H₂O and protein stock must we add to get this?

Answer 1

a)
density = 0.25 mg/ml
mass = 20 gm = 20000mg
volume required = mass/ density
                        = 20,000/0.25
                        =80,0000 mL
                        = 80 L
Answer: 80 L

b)
density = 0.25 mg/ml
mass = 150 gm = 150000mg
volume required = mass/ density
                        = 150,000/0.25
                        =600,0000 mL
                        = 600 L
To start with we need 600 L of solution.

Final:
density = 0.5 mg/ml
mass = 150 gm = 150000mg

volume required = mass/ density
                        = 150,000/0.5
                        =300,0000 mL
                        = 300 L
We need 300 L of H2O.

d)
you need 1*10=10 gm of protein
density = 0.25 mg/ml
mass = 10 gm = 10.000mg
volume required = mass/ density
                        = 10,000/0.25
                        =40,0000 mL
                        = 40 L
To start with we need 40 L of solution.
Final:
density = 10 g/mL
mass = 10 gm

volume required = mass/ density
                        = 10/10
                        =1 mL
                      
We need 1 mL of H2O

e)
you need 100*0.1=10 gm of protein
density = 0.25 mg/ml
mass = 10 gm = 10.000mg
volume required = mass/ density
                        = 10,000/0.25
                        =40,0000 mL
                        = 40 L
To start with we need 40 L of solution.
Final:
density = 0.1 g/l
mass = 10 gm

volume required = mass/ density
                        = 10/0.1
                        =100 L
                      
We need 100 L of H2O