Solving Chemistry Problem: Reactions, CO2 & Volumes

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In summary, 40 cm3 of gas is reacted with 40 cm3 of oxygen, producing hydrogen and carbon monoxide. After cooling to room temperature, the volume decreases to 51 cm3. Addition of concentrated KOH results in a further decrease to 41 cm3 due to the absorption of CO2. The equations for the reactions are 2 H2 (g) + O2 (g) > 2 H2O (l) and 2 CO (g) + O2 (g) > 2 CO2 (g). The relative volumes of gaseous reactants to products are 3 : 2. The volume of carbon dioxide produced is 10 cm3. The volume of carbon monoxide in
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CarlosMarti12
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Homework Statement

40 cm3 of a gas was exploded with 40 cm3 of oxygen (known to be in excess). Under the conditions used, only hydrogen and carbon monoxide reacted with oxygen. On cooling the mixture to room temperature, the volume was 51 cm3. On adding concentrated KOH, the volume decreased further to 41 cm3 as CO2 was absorbed.

a. Write equations (including the state symbols at room temperature) for the reactions which occur on explosion.

b. What are the relative volumes of gaseous reactants to gaseous products in these reactions?

c. What volume of carbon dioxide is produced?

d. What is the volume of carbon monoxide in the original 40 cm3 of gas?

e. What is the total decrease in volume as a result of the explosion?

f. What decrease in volume is caused by (1) CO and (2) H2 on explosion?

g. What are the volumes of (1) H2 and (2) N2 in the original 40 cm3 of gas?

The attempt at a solution

a. 2 H2 (g) + O2 (g) > 2 H2O (l)
2 CO (g) + O2 (g) > 2 CO2 (g)
b. 2 + 1 : 2 = 3 : 2

I feel like I'm missing something really obvious after that...
 
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  • #2
When adding the KOH, 51-41=10 cm^3 CO2 is absorbed. From this you know the amount of CO as well, because each CO2 molecule is produced from one CO.

The decrease of the volume is due to the liquid H2O (the volume of the liquid can be neglected when compared to the volume of the gas), which comes from H2, so from this you can calculate the amount of H2 in the original gas.

So you know the volume of CO and H2. Hopefully, their sum is less then 40 cm^3 :)
The rest must be N2, which does not react with oxygen (in this setup).
 

FAQ: Solving Chemistry Problem: Reactions, CO2 & Volumes

1. What are the steps to solving a chemistry problem involving reactions, CO2, and volumes?

First, identify the reactants and products in the chemical equation. Then, balance the equation by ensuring that the number of atoms of each element is the same on both sides. Next, determine the limiting reactant and use it to calculate the theoretical yield. Finally, use the ideal gas law to calculate the volume of CO2 produced.

2. How do I know which reactant is the limiting reactant?

To determine the limiting reactant, calculate the moles of each reactant using its molar mass and the given mass or volume. Then, divide the number of moles by the coefficient in front of the reactant in the balanced equation. The reactant with the lowest value is the limiting reactant.

3. What is the ideal gas law and how is it used in solving chemistry problems?

The ideal gas law is PV = nRT, where P is the pressure, V is the volume, n is the number of moles, R is the ideal gas constant, and T is the temperature in Kelvin. It is used to calculate the volume of a gas produced in a chemical reaction, given the number of moles and the temperature and pressure conditions.

4. What are the units for pressure, volume, and temperature in the ideal gas law?

The units for pressure are usually in atmospheres (atm), but can also be in kilopascals (kPa) or millimeters of mercury (mmHg). Volume is typically measured in liters (L) or milliliters (mL). Temperature must be in Kelvin (K), which is equal to degrees Celsius plus 273.15.

5. Are there any shortcuts or tricks for solving chemistry problems involving reactions, CO2, and volumes?

One helpful shortcut is to convert all units to moles, as it makes calculations easier. You can also use the molar volume of a gas at STP (standard temperature and pressure), which is 22.4 L/mol. Additionally, always double check your work and make sure your final answer is reasonable based on the given information.

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