El volumen del estómago de un adulto fluctúa entre 50 mL cuando está vacio y 1 L cuando está l

El volumen del estómago de un adulto fluctúa entre 50 mL...

$\mathrm{El}$ volumen del estómago de un adulto fluctúa entre $50 \mathrm{~mL}$ cuando está vacio y $1 \mathrm{~L}$ cuando está lleno. Si su volumen es de $400 \mathrm{~mL}$ y su contenido tiene un $\mathrm{pH}$ de 2 , ¿cuántos moles de $\mathrm{H}^{+}$contiene? Suponiendo que todo el $\mathrm{H}^{+}$proviene de $\mathrm{HCl}$, ¿cuántos gramos de hidrogenocarbonato de sodio neutralizarán totalmente el ácido del estómago?

Key Concepts

Stoichiometry and Mole Calculations

The stoichiometry concept involves using balanced equations to relate the amounts (in moles) of reactants to products. This is essential for calculating how many moles of one substance will react with or neutralize another based on their mole ratios.

Molar Mass and Unit Conversions

This concept refers to the conversion from moles to grams by using the molar mass of a compound. Converting the amount in moles to grams involves multiplying by the compound’s molar mass, making it a key step in translating theoretical stoichiometric predictions to practical measurements.

Acid-Base Neutralization Reactions

This concept covers the chemical reaction where an acid reacts with a base to produce a salt and water. In stoichiometric calculations, the balanced chemical equation is used to determine the proper mole ratios between the acid and the base for complete neutralization.

Volume and Molarity Relationship

This concept involves using the relationship between volume and molarity to calculate the number of moles present. By converting the volume into liters and multiplying by the molarity (moles per liter), you obtain the total moles of a given substance in that volume.

pH and Hydrogen Ion Concentration

This concept explains that the pH is a measure of hydrogen ion concentration in a solution. Since pH is defined as the negative logarithm of the hydrogen ion concentration (pH = -log[H?]), knowing the pH allows you to calculate the molarity of H? ions in any given solution.

Transcript

00:01 Chapter 16, problem 118, the volume of an adult stomach ranges from about 50 milliliters when empty to one liter when full.

00:09 The stomach volume is 400 milliliters and it contains to have a ph of 2.

00:18 How many moles of h -plus does the stomach contain? and then assuming that all the h -plus comes from h -tl, how many grams of sodium hydrogen carbonate will totally neutralize the stomach acidity? so the first thing to note here is that it says if the stomach volume is 40 milliliters and contains to have a ph of 2, we are going to be looking at a volume of 400 milliliters for the ph at 2.

00:48 So the first thing we need to do is find the concentration of h plus to then find the moles of h plus.

00:54 So to do that, we're going to do our h plus concentration is equal to 10 to the negative p.

01:03 And so we're going to do 10 to the negative 2.

01:06 And when we plug the entire calculator, you get 0 .01 molar solution.

01:12 So now, since we have the molarity, now we need to find our moles.

01:15 So molarity is equal to moles over liters.

01:21 One important thing is whenever you are using this equation, your volume has to be in liters.

01:29 And so what you're going to do is you're going to do 400, mean, milllele, and convert that to liters.

01:36 So there's a thousand milliliters and one liter, and so therefore you get 0 .4 liters.

01:44 So going back to the equation of molarity is equal to moles per liter.

01:49 To find your moles, you just multiply over your liters.

01:53 So moles times liters will give you your moles.

01:57 So you're going to do 0 .01 times 0 .4.

02:02 And so when you plug that into the calculator, you get 0 .004.

02:10 So that is how many moles of h plus is in the stomach...

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