guided case study
in january 2024, the door blew off an alaska airlines flight,
causing the airplane cabin to depressurize.
when a plane depressurizes, oxygen
masks are automatically released
from compartments in the ceiling of
the cabin. if youve ever heard a pre-
flight speech, you know that \oxygen
is flowing through the mask even
though the bag does not inflate\. but
where is this oxygen coming from?
pressurized oxygen tanks are too heavy and dangerous to be stored
aboard airplanes. instead, oxygen in some airplanes is delivered by
a chemical oxygen generation system, commonly known as an
\oxygen candle\. in an oxygen candle, oxygen gas is produced by
the burning of a solid compound.
when a passenger pulls on the oxygen mask, a firing pin is released,
which heats solid sodium chlorate and causes it to decompose into
sodium chloride and oxygen. this reaction also produces more heat,
causing the sodium chlorate to continue burning until it is used up.
the oxygen produced by this reaction can usually last long enough
for the pilot to descend to 10,000 ft where supplementary oxygen is
no longer needed.
name:
1. write the chemical reaction for the oxygen candle and balance it
2. if it took the alaska airlines pilot 8.2 minutes to safely descend to 10,000
feet, how many liters of oxygen would each passenger need? show your
work in dimensional analysis format.
(humans typically need 500 liters of oxygen per day)
3. based on your previous answer, how many grams of sodium chlorate would
be required to produce that amount of oxygen? show your work in
dimensional analysis format. (assume standard temperature & pressure)
4. the boeing factory needs to know how much solid sodium to purchase for
the oxygen candles. if one plane has 150 seats, how many kg of sodium will
boeing need to produce the oxygen candles for 10 planes? (assume the
same 8.2 minute oxygen requirement.)
5. historically, oxygen candles were used as a source of oxygen for japanese
pilots during world war ii. a downfall of these early oxygen candles was a
side reaction that produced toxic chlorine gas, which is toxic to humans.
the side reaction that occurred was: 4naclo₃ → 2na₂o + 5o₂ + 2cl₂
to eliminate this chlorine gas, barium peroxide (bao₂) was added to the
oxygen candle which converts the chlorine gas into harmless barium chloride
and additional oxygen gas.
write the formula for the reaction between barium peroxide and
chlorine gas.
6. what type of chemical reaction is occurring in the previous question?

Question

Accepted Answer

### Question 1:
# Explanation:
## Step1: Identify the reaction
The solid compound is sodium chlorate ($\ce{NaClO3}$) which decomposes into sodium chloride ($\ce{NaCl}$) and oxygen ($\ce{O2}$). The unbalanced reaction is $\ce{NaClO3(s) -> NaCl(s) + O2(g)}$.

## Step2: Balance the reaction
- For Na: 1 on left, 1 on right (balanced).
- For Cl: 1 on left, 1 on right (balanced).
- For O: 3 on left, 2 on right. Find LCM of 3 and 2, which is 6. So put 2 in front of $\ce{NaClO3}$ (gives 6 O) and 3 in front of $\ce{O2}$ (gives 6 O). Then adjust Na and Cl: put 2 in front of $\ce{NaCl}$. The balanced reaction is $\ce{2NaClO3(s) -> 2NaCl(s) + 3O2(g)}$.

# Answer: $\ce{2NaClO3(s) -> 2NaCl(s) + 3O2(g)}$

### Question 2:
# Explanation:
## Step1: Convert time to days
Time = 6.2 minutes. There are 1440 minutes in a day (24 hours * 60 minutes/hour). So fraction of day = $\frac{6.2}{1440}$ days.

## Step2: Calculate oxygen needed
Humans need 500 liters per day. So oxygen needed = $500\ 	ext{L/day} 	imes \frac{6.2}{1440}\ 	ext{day}$

Calculate: $\frac{500 	imes 6.2}{1440} = \frac{3100}{1440} \approx 2.15\ 	ext{liters}$ (rounded to two decimal places)

# Answer: Approximately $\boldsymbol{2.15}$ liters (or exact value $\boldsymbol{\frac{3100}{1440} = \frac{155}{72} \approx 2.15}$ liters)

### Question 3:
# Explanation:
## Step1: Recall moles of $\ce{O2}$ from Q2
From Q2, $V = 2.15\ 	ext{L}$ (at STP, 1 mole of gas = 22.4 L). Moles of $\ce{O2}$, $n_{\ce{O2}} = \frac{V}{22.4} = \frac{2.15}{22.4}\ 	ext{mol}$

## Step2: Relate moles of $\ce{O2}$ to $\ce{NaClO3}$ from balanced reaction
From $\ce{2NaClO3 -> 2NaCl + 3O2}$, 3 moles $\ce{O2}$ come from 2 moles $\ce{NaClO3}$. So moles of $\ce{NaClO3}$, $n_{\ce{NaClO3}} = n_{\ce{O2}} 	imes \frac{2}{3}$

## Step3: Calculate mass of $\ce{NaClO3}$
Molar mass of $\ce{NaClO3}$: Na (23) + Cl (35.5) + 3*O (16) = 23 + 35.5 + 48 = 106.5 g/mol. Mass = $n_{\ce{NaClO3}} 	imes 106.5$

First, $n_{\ce{O2}} = \frac{2.15}{22.4} \approx 0.09598\ 	ext{mol}$

$n_{\ce{NaClO3}} = 0.09598 	imes \frac{2}{3} \approx 0.06399\ 	ext{mol}$

Mass = $0.06399\ 	ext{mol} 	imes 106.5\ 	ext{g/mol} \approx 6.81\ 	ext{grams}$ (rounded to two decimal places)

# Answer: Approximately $\boldsymbol{6.81}$ grams (or follow exact calculation from Q2's exact value)

### Question 4:
# Explanation:
## Step1: Moles of $\ce{NaCl}$ from Q3
From balanced reaction $\ce{2NaClO3 -> 2NaCl + 3O2}$, moles of $\ce{NaCl}$ = moles of $\ce{NaClO3}$ (from Q3, $n_{\ce{NaClO3}} \approx 0.06399\ 	ext{mol}$, so $n_{\ce{NaCl}} = 0.06399\ 	ext{mol}$ per passenger)

## Step2: Moles for 1 plane (150 seats)
Moles per plane = $0.06399\ 	ext{mol/passenger} 	imes 150\ 	ext{passengers} = 9.5985\ 	ext{mol/plane}$

## Step3: Moles for 10 planes
Moles for 10 planes = $9.5985\ 	ext{mol/plane} 	imes 10 = 95.985\ 	ext{mol}$

## Step4: Mass of $\ce{NaCl}$
Molar mass of $\ce{NaCl}$: 23 + 35.5 = 58.5 g/mol. Mass = $95.985\ 	ext{mol} 	imes 58.5\ 	ext{g/mol} = 5615.12\ 	ext{g} = 5.615\ 	ext{kg}$ (rounded to three decimal places)

# Answer: Approximately $\boldsymbol{5.62}$ kg (or exact value based on precise calculations)

### Question 5:
# Explanation:
## Step1: Identify reactants and products
Reactants: Barium peroxide ($\ce{BaO2}$) and chlorine gas ($\ce{Cl2}$)

Products: Barium chloride ($\ce{BaCl2}$) and oxygen gas ($\ce{O2}$) (and maybe water? Wait, the problem says "converts the chlorine gas into barium chloride and additional oxygen gas". So reaction: $\ce{BaO2 + Cl2 -> BaCl2 + O2}$

## Step2: Balance the reaction
- Ba: 1 on left, 1 on right (balanced)
- Cl: 2 on left, 2 on right (balanced)
- O: 2 on left, 2 on right (balanced). Wait, but let's check: $\ce{BaO2 + Cl2 -> BaCl2 + O2}$ is already balanced? Wait, no: $\ce{BaO2}$ has 2 O, $\ce{O2}$ has 2 O. So yes, balanced as $\ce{BaO2 + Cl2 -> BaCl2 + O2}$? Wait, no, maybe a typo. Wait, maybe it's $\ce{BaO2 + Cl2 -> BaCl2 + O2}$ but let's check oxidation states. BaO2: Ba is +2, O is -1 (peroxide). Cl2 is 0. BaCl2: Ba +2, Cl -1. O2 is 0. So BaO2 is oxidized (O from -1 to 0) and Cl2 is reduced (Cl from 0 to -1). So the reaction is $\ce{BaO2 + Cl2 -> BaCl2 + O2}$ (balanced as is? Wait, Ba:1, Cl:2, O:2 on left; Ba:1, Cl:2, O:2 on right. Yes, balanced.

# Answer: $\ce{BaO2 + Cl2 -> BaCl2 + O2}$ (or check if there's water, but problem says "additional oxygen gas", so likely this)

### Question 6:
# Explanation:
## Step1: Identify reaction type
The reaction in Q5 is $\ce{BaO2 + Cl2 -> BaCl2 + O2}$. Here, BaO2 is oxidized (O goes from -1 to 0) and Cl2 is reduced (Cl goes from 0 to -1). So it's a redox reaction, specifically a single displacement? Wait, no, it's a reaction where one element is oxidized and another is reduced. Alternatively, it's a redox reaction where BaO2 is a reducing agent (oxidized) and Cl2 is an oxidizing agent (reduced). But also, it can be seen as a displacement: O in BaO2 is displaced by Cl? No, better: it's a **redox reaction** (oxidation-reduction reaction) because there's a transfer of electrons (change in oxidation states: O from -1 to 0, Cl from 0 to -1).

# Answer: Oxidation - Reduction Reaction (or Redox Reaction)

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QUESTION IMAGE

Question

Explanation:

Question 1:

Step1: Identify the reaction

Step2: Balance the reaction

Step1: Convert time to days

Step2: Calculate oxygen needed

Step1: Recall moles of $\ce{O2}$ from Q2

Step2: Relate moles of $\ce{O2}$ to $\ce{NaClO3}$ from balanced reaction

Step3: Calculate mass of $\ce{NaClO3}$

Answer:

Question 2: