The reaction of sodium peroxide (Na2 O2) with CO2 is used in space vehicles to remove CO2 from t

The reaction of sodium peroxide (Na2 O2) with CO2 is used in...

The reaction of sodium peroxide $\left(\mathrm{Na}_{2} \mathrm{O}_{2}\right)$ with $\mathrm{CO}_{2}$ is used in space vehicles to remove $\mathrm{CO}_{2}$ from the air and generate $\mathrm{O}_{2}$ for breathing: $$ 2 \mathrm{Na}_{2} \mathrm{O}_{2}(s)+2 \mathrm{CO}_{2}(g) \longrightarrow 2 \mathrm{Na}_{2} \mathrm{CO}_{3}(s)+\mathrm{O}_{2}(g) $$ (a) Assuming that air is breathed at an average rate of 4.50 $\mathrm{L} / \mathrm{min}\left(25^{\circ} \mathrm{C} ; 735 \mathrm{mm} \text { Hg) and that the concentration}\right.$ of $\mathrm{CO}_{2}$ in expelled air is 3.4$\%$ by volume, how many grams of $\mathrm{CO}_{2}$ are produced in 24 $\mathrm{h}$ ? (b) How many days would a 3.65 $\mathrm{kg}$ supply of $\mathrm{Na}_{2} \mathrm{O}_{2}$ last?

The reaction of sodium peroxide $\left(\mathrm{Na}_{2} \mathrm{O}_{2}\right)$ with $\mathrm{CO}_{2}$ is used in space vehicles to remove $\mathrm{CO}_{2}$ from the air and generate
$\mathrm{O}_{2}$ for breathing:
$$
2 \mathrm{Na}_{2} \mathrm{O}_{2}(s)+2 \mathrm{CO}_{2}(g) \longrightarrow 2 \mathrm{Na}_{2} \mathrm{CO}_{3}(s)+\mathrm{O}_{2}(g)
$$
(a) Assuming that air is breathed at an average rate of 4.50 $\mathrm{L} / \mathrm{min}\left(25^{\circ} \mathrm{C} ; 735 \mathrm{mm} \text { Hg) and that the concentration}\right.$ of $\mathrm{CO}_{2}$ in expelled air is 3.4$\%$ by volume, how many grams of $\mathrm{CO}_{2}$ are produced in 24 $\mathrm{h}$ ?
(b) How many days would a 3.65 $\mathrm{kg}$ supply of $\mathrm{Na}_{2} \mathrm{O}_{2}$ last?

Key Concepts

Stoichiometry

Stoichiometry is the branch of chemistry that deals with the quantitative relationships between reactants and products in a chemical reaction. It uses the coefficients in a balanced chemical equation to determine how many moles, as well as masses or volumes, of reactants are needed to produce a desired amount of product, or vice versa.

Ideal Gas Law

The Ideal Gas Law, summarized by the equation PV = nRT, connects the pressure, volume, temperature, and number of moles of an ideal gas. This principle is crucial for converting between gas volumes and moles under specified conditions, which is essential for quantitative gas-phase calculations.

Mole Concept

The mole concept is fundamental in chemistry as it provides a direct link between the mass of a substance and the number of its constituent particles. It allows chemists to count entities like atoms and molecules using mass measurements, by applying Avogadro’s number in conversion processes.

Unit Conversion

Unit conversion is an essential technique that ensures all measurements in chemical calculations are expressed in consistent units. This concept involves converting values between different units of volume, time, pressure, temperature, and mass, so that equations and formulas can be applied accurately.

Gas Mixtures and Concentrations

Understanding gas mixtures and concentrations is key when dealing with compounds that are part of a larger mixture. It involves calculating the portion or percentage of one gas within a mixture, typically expressed by volume percent or mole fraction, which is important for determining the quantity of a specific gas in a system.

Transcript

00:03 So this first question, we have an oxygen scrubber, or co2 scrubber, rather, in space using sodium peroxide.

00:11 So sodium peroxide and carbon dioxide gas combined to make sodium carbonate an oxygen gas.

00:17 And we're told that we have 4 .50 liters per minute.

00:21 That's the rate at which we have exhalation.

00:26 At 25 degrees celsius and 735 millimeters of mercury, we're also told.

00:33 That it is 3 .4 % co2.

00:40 And the question that we're asked is how many grams of co2 are created in a day for part one? and so the way we would go about this, the first thing we'd do is we would convert this into moles per minute.

00:53 So we take our 4 .5, for every minute we make 4 .5 liters.

00:58 So we can use our ideal gas law.

01:02 Pv equals nrt.

01:05 Trying to solve for n in this case.

01:08 So we've got n equals pv over r t.

01:16 And so we're going to do p is 735 times v is 4 .5.

01:27 Divide by r when we're dealing with millimeters of mercury, r is going to be 62 .4.

01:34 And t, we're at 25 celsius, which, as always, we have to convert into kelvin.

01:40 So that's 298 kelvin.

01:44 And that gives us a total of 735 times 4 .5, divide 62 .4, divide 298, 0 .178 liters.

02:02 Nope, moles per minute.

02:07 But that's everything, right? that's not just the co2.

02:11 So we also need to, i think what i'm going to do first, i'm going to convert this to days.

02:18 So we have 60 minutes in an hour, 24 hours in a day, and that gives us 256 .13 moles per day.

02:38 And again, that's everything...

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