How many grams are there in 2.75E23 molecules of C2H6 (MM = 30 grams)?

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lisacarter0804

28.05.2023

Chemistry

The expression for in an aqueous solution is $\boxed{{{\text{k}}_{{\text{a1}}}} = \frac{{\left[ {{\text{HCO}}_3^ - } \right]\left[ {{{\text{H}}_{\text{3}}}{{\text{O}}^ + }} \right]}}{{\left[ {{{\text{H}}_2}{\text{C}}{{\text{O}}_3}} \right]}}}$ .

Further Explanation:

Acids:

These are the type of substances that are known for hydrogen ion donation in aqueous solutions. In other words, proton donors are called acids. Based on the number of protons donated by acids, these can be classified as monoprotic and polyprotic, the description of which is given below.

Monoprotic acids

“Mono” means “single” while “protic” refers to “protons”. So monoprotic acids are those acidshaving capacityto donate single proton in aqueous solutions. HCl, HI and HF can donate single proton in solutions, thereby acting as monoprotic acids.

Polyprotic acids

“Poly” means “many” while “protic” refers to “protons”. So polyprotic acids are those acids having capacity to donate more than oneproton in aqueous solutions. ${{\text{H}}_{\text{3}}}{\text{P}}{{\text{O}}_{\text{4}}}$ , ${{\text{H}}_{\text{2}}}{\text{C}}{{\text{O}}_{\text{3}}}$ and ${{\text{H}}_{\text{2}}}{\text{S}}{{\text{O}}_{\text{4}}}$ can donate more than one proton in solutions, thereby acting as monoprotic acids.

Dissociation constant

It is a parameter required to determine strength of acids and is represented by .

As is evident from chemical formula of carbonic acid $\left( {{{\text{H}}_{\text{2}}}{\text{C}}{{\text{O}}_{\text{3}}}} \right)$ , it has two hydrogens available for donation in solutions. Therefore ${{\text{H}}_{\text{2}}}{\text{C}}{{\text{O}}_{\text{3}}}$ acts as diprotic acid.

Dissociation of ${{\text{H}}_{\text{2}}}{\text{C}}{{\text{O}}_{\text{3}}}$ occurs as follows:

$\text{H}_{2}\text{CO}_{3}(aq)+\text{H}_{2}\text{O}(aq)_{\rightleftharpoons}^{{K}_{a1}}\text{HCO}^{-}_{3}(aq)+\text{H}_{3}\text{O}^{+}(aq)\\\text{HCO}^{-}_{3}}(aq)+\text{H}_{2}\text{O}(aq)_{\rightleftharpoons}^{{K}_{a2}}\text{CO}^{2-}_{3}(aq)+\text{H}_{3}\text{O}^{+}(aq)$

Where ${{\text{k}}_{{\text{a1}}}}$ and ${{\text{k}}_{{\text{a2}}}}$ are first and second dissociation constants of ${{\text{H}}_{\text{2}}}{\text{C}}{{\text{O}}_{\text{3}}}$ respectively.

Since water is always present in larger quantity, its concentration is neglected while writing the expressions for dissociation constant of acid.

The expression of ${{\text{k}}_{{\text{a1}}}}$ for ${{\text{H}}_{\text{2}}}{\text{C}}{{\text{O}}_{\text{3}}}$ is as follows:

${{\text{k}}_{{\text{a1}}}} = \dfrac{{\left[ {{\text{HCO}}_3^ - } \right]\left[ {{{\text{H}}_{\text{3}}}{{\text{O}}^ + }} \right]}}{{\left[ {{{\text{H}}_2}{\text{C}}{{\text{O}}_3}} \right]}}$

Learn More:

Write the chemical equation responsible for pH of buffer containing and : Reason for the acidic and basic nature of amino acid.

Answer details:

Grade: High School

Subject: Chemistry

Chapter: Acids, bases and salts

Keywords: H2CO3, acid, dissociation constant, ka2, H2O, H3O+, H2CO3,HCO3-, CO32-, ka1, hydrogens, monoprotic acid, polyprotic acid, expression, strength of acids, ka.

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