You are given stocks of 4 m nacl, 40% glucose, and 1m tris-hcl (ph 8.5). you need to make 400 ml of a buffer containing 0.5 m nacl, 8% glucose and 50 mm tris-hcl (ph 8.5). how would you make the buffer?

50mL of 4M NaCl, 80mL of 40% glucose, 20mL of 1M Tris-HCl (pH 8.5) and 250mL of water.

Explanation:

To make 400mL containing 0.5M NaCl you need to add:

4M / 0.5M = 8 (dilution 1/8). 400mL / 8 = 50 mL of 4M NaCl.

Glucose 8% you need to add:

40% / 8% = 5 (dilution 1/5). 400mL / 5 = 80 mL of 40% glucose

Buffer 50mM you need to add:

1000mM / 50mM = 20 (dilution 1/20). 400mL / 20 = 20mL of 1M Tris-HCl (pH 8.5)

The resting volume: 400mL - 50mL of 4M NaCl - 80mL of 40% glucose - 20mL of 1M Tris-HCl (pH 8.5) = 250 mL must be completed with water.

Thus, to make the solution you need: 50mL of 4M NaCl, 80mL of 40% glucose, 20mL of 1M Tris-HCl (pH 8.5) and 250mL of water.

I hope it helps!

the molecules move in straight line until they collide with each other or with the walls of the container. collisions are perfectly elastic; when two molecules collide, they change their directions and kinetic energies, but the total kinetic energy is conserved.

explanation:

assuming that your periodic table has eighteen columns, you should highlight   the four elements in the third column from the left of the table.

neutral atoms of elements after calcium contain d electrons. the energy of d orbitals of a particular main shell lies between the energy of the s and p orbitals of the next main shell. for example, electrons in the have energy higher than those in the orbital while lower than those of the orbital.

by the aufbau principle, electrons fill orbitals one at a time, starting from those of the lowest energy. the orbital is therefore filled right after orbitals and before orbitals.  

potassium has electron configuration and calcium . the s orbital of a main shell holds a maximum of two electrons. the next element would thus have the electron configuration and satisfy the requirements.

a neutral atom of the element contains three electrons on top of the most recent noble gas element. it should thus be placed in the third column of the periodic table. both scandium and yttrium would satisfy the conditions. an aufbau diagram indicates that the 4f orbital is filled before the 5d. however, it appears that exceptions exists for both lanthanum and actinium. neutral atoms of the two d-block elements also demonstrate the and should be highlighted as well.