You have a 5 M NaCl stock solution. (NaCl F. W. is 58.4) a) How much NaCl (in g) do you need to make 1 liter of the 5 M stock solution? b) How much stock solution will you need if you want to make 100 ml of 50 mM NaCl? c) What is the % concentration of a 50 mM solution of NaCl?

a) 292.0 g

b) 1 ml

c) 0.29 %

Explanation:

a) The amount of NaCl can be calculated as follows:

Where:

m: is the mass of NaCl =?

C: is the concentration of NaCl = 5M

V: is the volume = 1 L

M: is the molar mass of NaCl = 58.4 g/mol

Hence, you need to take 292.0 g of NaCl to make 1 L of 5 M stock solution.

b) We need to use the following equation to find the quantity of stock solution that is needed to make 100 ml of 50 mM of NaCl:

Where:

C₁: is the initial concentration = 5 M

V₁: is the volume of the initial concentration =?          

C₂: is the concentration of the solution to prepare = 50 mM

V₂: is the volume of the solution to prepare = 100 ml

Therefore, you need 1 ml of the stock solution to make 100 ml of 50 mM NaCl.

c) The % concentration of a 50 mM solution of NaCl is:

Hence, the % concentration is 0.29 % (w/v).

I hope it helps you!

- calcium has greater affinity to bond with electron receptors than hydrogen does and hence, it has the ability to replace hydrogen in most of its compounds.

- lithium has 2 valence electrons in the product because it can make only 1 bond with hydrogen. beryllium has 4 valence electrons in the product because it can only make 2 bonds. it has fewer electrons than neon and can react with electron donors. each hydrogen has 2 valence electrons, the same as helium.

- the covalent bond formed between carbon and hydrogen is polar because carbon is more electronegative than hydrogen and it attracts the bonded electron pair closer to itself, thus giving hydrogen a partial positive charge.

- a hydrogen bond is a relatively weak bond that hydrogen atoms make with the electronegative atoms nitrogen, oxygen or fluorine.

so the best choice is a.) 2 calcium (ca) atoms