En los últimos 40 años, los niveles atmosféricos de CO2 han aumentado en cerca del 20 %, de 315

En los últimos 40 años, los niveles atmosféricos de CO2 han...

En los últimos 40 años, los niveles atmosféricos de $\mathrm{CO}_2$ han aumentado en cerca del $20 \%$, de $315 \mathrm{ppm}$ a $375 \mathrm{ppm}$. (a) Dado que hoy en dia el $\mathrm{pH}$ promedio de la lluvia limpia y no contaminada es de 5.4, determine el $\mathrm{pH}$ de la lluvia no contaminada de hace 40 años. Suponga que el ácido carbónico $\left(\mathrm{H}_2 \mathrm{CO}_3\right)$ formado por la reacción de $\mathrm{CO}_2$ con agua es el único factor que influye en el $\mathrm{pH}$. $$ \mathrm{CO}_2(\mathrm{~g})+\mathrm{H}_2 \mathrm{O}(l) \rightleftharpoons \mathrm{H}_2 \mathrm{CO}_3(a c) $$ (b) ¿Qué volumen de $\mathrm{CO}_2$ a $25^{\circ} \mathrm{C}$ y $1 \mathrm{~atm}$ se disuelve en un cubo de 20.0 L de agua de lluvia actual?

En los últimos 40 años, los niveles atmosféricos de $\mathrm{CO}_2$ han aumentado en cerca del $20 \%$, de $315 \mathrm{ppm}$ a $375 \mathrm{ppm}$. (a) Dado que hoy en dia el $\mathrm{pH}$ promedio de la lluvia limpia y no contaminada es de 5.4, determine el $\mathrm{pH}$ de la lluvia no contaminada de hace 40 años. Suponga que el ácido carbónico $\left(\mathrm{H}_2 \mathrm{CO}_3\right)$ formado por la reacción de $\mathrm{CO}_2$ con agua es el único factor que influye en el $\mathrm{pH}$.
$$
\mathrm{CO}_2(\mathrm{~g})+\mathrm{H}_2 \mathrm{O}(l) \rightleftharpoons \mathrm{H}_2 \mathrm{CO}_3(a c)
$$
(b) ¿Qué volumen de $\mathrm{CO}_2$ a $25^{\circ} \mathrm{C}$ y $1 \mathrm{~atm}$ se disuelve en un cubo de 20.0 L de agua de lluvia actual?

Key Concepts

pH and Acid?Base Equilibria

pH is a measure of the hydrogen ion concentration in a solution and is defined as the negative logarithm of that concentration. This concept is fundamental in acid–base chemistry because changes in the concentrations of acids or bases modify the pH of a solution, indicating its level of acidity or basicity. Understanding pH helps in analyzing how various chemical processes are affected by slight modifications in hydrogen ion concentration.

CO2 Dissolution and Carbonic Acid Formation

When carbon dioxide dissolves in water, it reacts with water to form carbonic acid, a weak acid. This equilibrium process (CO2 + H2O ? H2CO3) is important because it explains how changes in dissolved CO2 concentration can lead to changes in the acidity of natural water bodies, such as rainwater. The formation of carbonic acid is the primary factor affecting the pH of rain not impacted by other pollutants.

Henry’s Law

Henry’s Law relates the concentration of a gas in a liquid to the partial pressure of that gas above the liquid. It is an essential concept when dealing with the dissolution of gases like CO2 in aqueous solutions, allowing for the calculation of how much gas dissolves under given temperature and pressure conditions. This law provides a quantitative link between atmospheric levels of CO2 and its corresponding concentration in rainwater.

Ideal Gas Law

The Ideal Gas Law (PV = nRT) is used to relate the pressure, volume, temperature, and moles of a gas. This principle is useful for determining the volume that a given amount of gas occupies under specified conditions, such as 25°C and 1 atm, and is fundamental in calculations involving the behavior of gases in different environments.

Transcript

00:01 Atmospheric carbon dioxide levels have risen nearly 20 % over the past 40 years.

00:17 This is sort of an older tax, so they've risen more than that now.

00:22 And they've risen from 315 parts per million to 380 parts per million.

00:31 And of course they're up more than that now.

00:39 A, given that the average ph of clean, unpolluted rain today is 5 .4.

00:48 So let's figure out the ph.

00:49 Of unpolluted rain for each, 40 years ago.

01:07 We're going to assume the carbonic acid formed by the reaction of co2 and water is the only factor influencing ph.

01:32 I've just got to go make sure that in my problem there's nothing up here.

01:37 Okay, that's a and then there is a b.

01:40 I'll do the b after we get too ready for it.

01:45 Okay.

01:49 Let's get that h plus concentration.

01:51 Current h plus concentration equals 10 to the negative 5 .4, which equals 3 .98 times 10 to the minus 6th molar.

02:14 Then we're going to use these values to solve for the h plus of the clean, polluted, unpolluted air back in the day.

02:29 So there's the current parts per million.

02:33 There's the olden days parts per million.

02:37 Here's the h plus we're solving for, and here's the 3 .98 times 10 to the minus 6 molar.

02:52 Solving for h plus, we get 4 .80 times 10 to the minus 6 molar.

03:11 I am looking at this, thinking this is backwards.

03:30 Then to get the ph, that will be the negative log of 4 .80 times 10 to the minus 6 molar, and that will be 5 .32.

03:45 So that was the ph back in the day.

03:51 Part b, let's see what part b asked us to do.

03:59 What volume of co2 at 25 degrees celsius and what point zero atmosphere pressure is dissolved in a 20 .0 liter bucket of today's rainwater.

04:43 Okay, this shouldn't be too...

Please give Ace some feedback