In the natural oxidation of hydrogen sulfide released by...

In the natural oxidation of hydrogen sulfide released by decaying organic matter, the following reaction occurs: $2 \mathrm{H}_{2} \mathrm{S}+$ $3 \mathrm{O}_{2} \rightarrow 2 \mathrm{SO}_{2}+2 \mathrm{H}_{2} \mathrm{O} .$ How many milliliters of hydrogen sul- fide, measured at $19^{\circ} \mathrm{C}$ and 549 torr, will be used in a reaction that also uses $704 \mathrm{mL} \mathrm{O}_{2}$ at 159 torr and $26^{\circ} \mathrm{C} ?$

In the natural oxidation of hydrogen sulfide released by decaying organic matter, the following reaction occurs: $2 \mathrm{H}_{2} \mathrm{S}+$ $3 \mathrm{O}_{2} \rightarrow 2 \mathrm{SO}_{2}+2 \mathrm{H}_{2} \mathrm{O} .$ How many milliliters of hydrogen sul-
fide, measured at $19^{\circ} \mathrm{C}$ and 549 torr, will be used in a reaction that also uses $704 \mathrm{mL} \mathrm{O}_{2}$ at 159 torr and $26^{\circ} \mathrm{C} ?$

Key Concepts

Ideal Gas Law

The ideal gas law (PV = nRT) is fundamental in understanding the behavior of gases. It provides the relationship between pressure, volume, temperature, and the number of moles, allowing for the conversion between volume and moles under given conditions. This is essential for any calculation involving gases under varying conditions.

Stoichiometry

Stoichiometry involves the quantitative relationships between reactants and products in a chemical reaction. It uses a balanced chemical equation to determine the proportionate amounts, in moles, of each substance involved, enabling the calculation of required amounts based on the reactants or expected yields of products.

Combined Gas Law

The combined gas law relates the pressure, volume, and temperature of a fixed amount of gas, and is used when these conditions change. It is particularly useful in converting the volume of a gas from one set of conditions to another, ensuring accurate comparisons and calculations between different states.

Gas Volume Corrections

Gas volume corrections are adjustments made when measuring gases under non-standard conditions. By accounting for differences in temperature and pressure, these corrections ensure that the measured gas volumes can be accurately related to moles of gas, facilitating precise stoichiometric calculations.

Transcript

00:01 Hi there.

00:02 This problem is another gas stoichiometry problem.

00:09 So to begin, we know we're going to need a balanced equation.

00:13 For any stoichiometry problem, we need a balanced equation.

00:18 We have two h2s, hydrogen sulfide, reacts with three oxygen molecules, to produce two sulfur dioxide, and two water molecules.

00:37 And these are gaseous products.

00:45 In fact, everything in this equation is a gas.

00:49 We are given 704 milliliters of the oxygen, and we are trying to calculate how many milliliters of the h2s we are going to need to react all 704 milliliters of the oxygen.

01:12 If these were at the same temperature and pressure, this would be a simple one -step problem using our coefficients as volume ratio.

01:21 Unfortunately, these are at different conditions of temperature and pressure.

01:26 The h2s is at 19 degrees celsius, converting that to kelvin right away.

01:34 That would be 292 kelvin.

01:39 And the h2s is at a pressure of 549 tor.

01:48 The oxygen gas, on the other hand, is at 2 .2.

01:50 26 degrees celsius.

01:55 Let me go ahead and change that immediately to kelvin.

01:59 That would be 299 kelvin.

02:04 And it's at 159 tour.

02:13 In order to use gas stoichiometry to solve this, i need to have both gases under the same conditions of temperature and pressure.

02:21 That means i am going to have to convert my volume of oxygen to a new volume, which it would be at the other conditions of temperature and pressure.

02:31 It looks like what i am going to need to use here is the combined gas law because i can plug in my initial conditions of pressure, volume, and temperature, and i can plug in the new pressure and the new temperature and solve for the new volume.

02:53 Once i get the new volume, then i can use gas stoichiometry...

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