How many milliliters of a 0.40 m solution of hydrochloric acid are necessary to neutralize 25 ml of a 0.20 m sodium hydroxide solution?

12.5 mL of HCl

Explanation:

The balanced chemical equation for the neutralization reaction is as follows

NaOH + HCl —> NaCl + H2O

Molar ratio of NaOH to HCl is 1:1

For neutralization to happen the number of NaOH moles is equal to the number of HCl moles

Number of NaOH moles reacted - 0.20 mol/L x 0.025 L = 0.005 mol

Therefore number of HCl moles reacted - 0.005 mol

Concentration of HCl is 0.40 mol/L

Concentration = number of moles / volume

Rearranging the equation

Volume = number of moles / concentration

Volume = 0.005 mol / 0.40 mol/L

= 0.0125 L

Volume of HCl added is 12.5 mL

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.