A student performed a serial dilution on a stock solution of 1.33 M NaOH. A 1.0 mL aliquot of the stock NaOH (ms) was added to 9 mL of water to make the first dilution (m1). Next, 1.0 mL of the m1 solution was added to 9 mL of water to make the second solution (m2). The processes was repeated for a total of 5 times. What is the final concentration of NaOH (m5)

The correct answer is 1.33 x 10⁻⁵ M

Explanation:

The concentration of the stock solution is: C= 1.33 M

In the first dilution, the student added 1 ml of stock solution to 9 ml of water. The total volume of the solution is 1 ml + 9 ml = 10 ml. So, the first diluted concentration is:

C₁= 1.33 M x 1 ml/10 ml = 1.33 M x 1/10 = 0.133 M

The second dilution is performed on C₁. The student added 1 ml of 0.133 M solution to 9 ml of water. Again, the total volume is 1 ml + 9 ml = 10 ml. The second diluted concentration is:

C₂= 0.133 M x 1 ml/10 ml = 0.133 M x 1/10= 0.0133 M

Since the student repeated the same dilution process 3 times more (for a total of 5 times), we have to multiply 5 times the initial concentration by the factor 1/10:

Final concentration = initial concentration x 1/10 x 1/10 x 1/10 x 1/10 x 1/10

                                = initial concentration x (1/10)⁵

                                = 1.33 M x 1 x 10⁻⁵

                                = 1.33 x 10⁻⁵ M

alkaline metals are lithium, sodium, rubidium, potassium, cesium and francium.

alkali metals have electronegativity from 0.7 to 1, lowest in periodic table of elements, which means that alkali metals (i group in periodic table) has positive oxidation number in compounds.

electronegativity is a chemical property that describes the tendency of an atom to attract a shared pair of electrons towards itself.

alkaline metals (far left in main group) have lowest ionizations energy and easy remove valence electrons,

for example, potassium is the alkali metal and has a single valence electron in the outer electron shell.

electron configuration of potassium is: ₁₉k 1s²2s²2p⁶3s²3p⁶4s¹.

they can not exist alone in nature, because they are very reactive.