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The ideal gas law is a fundamental principle in chemistry and physics that describes the behavior of gases under ideal conditions.
It combines several important gas laws into one equation:

• Boyle's Law states that the pressure of a gas is inversely proportional to its volume when temperature is held constant.
• Charles's Law shows that the volume of a gas is directly proportional to its temperature when pressure is constant.
• Avogadro's Law indicates that the volume of a gas is directly proportional to the number of moles of gas, assuming pressure and temperature are constant.

The ideal gas law formula is: \[ PV = nRT \] In this equation:

• P represents pressure,
• V is the volume,
• n denotes the number of moles,
• R is the universal gas constant (0.0821 L路atm鈦�(mol路K) for most practical purposes),
• and T is the temperature in Kelvin.

At Standard Temperature and Pressure (STP), which is defined as 273.15 Kelvin and 1 atmosphere of pressure, 1 mole of an ideal gas occupies 22.4 liters.
This is a handy approximation that simplifies calculations when you're dealing with gases.
In this exercise, the ideal gas law helps determine the volume of CO鈧� produced by combustion.

Molar mass is a critical concept when you're working with chemical reactions and stoichiometry.
It refers to the mass of one mole of a given substance.
Understanding molar mass is key to converting between moles鈥攁 measure of how many molecules or atoms there are鈥攁nd grams, which is a measure of mass.
To calculate a compound's molar mass, you must sum the atomic masses of all atoms present in the molecule.

• For example, the molar mass of carbon ( C) is 12.01 g/mol,
• while hydrogen ( H) is 1.01 g/mol.

In acetylene ( C鈧侶鈧�), you calculate the total molar mass by adding together the weighted contributions of each element: 2 times the molar mass of C (carbon) plus 2 times the molar mass of H (hydrogen).
This gives you a molar mass of 26.04 g/mol for acetylene, essential for converting its mass in grams into moles for further calculations.
This conversion allows you to utilize stoichiometry to determine the amounts of reactants and products.

Chemical reactions are processes where substances (reactants) change into new substances (products).
In this exercise, acetylene (C鈧侶鈧�) combusts with oxygen to produce water and carbon dioxide: \[2 \; \mathrm{C}_{2}\mathrm{H}_{2}(g) + 5 \; \mathrm{O}_{2}(g) \rightarrow 2 \; \mathrm{H}_{2}\mathrm{O}(g) + 4 \; \mathrm{CO}_{2}(g)\]This balanced equation tells us a lot about the reaction.

• The numbers in front of each molecule represent the stoichiometric coefficients.
• These coefficients indicate the ratios of moles of each substance involved in the reaction.

These are crucial in stoichiometry, a method used to calculate the relative quantities of reactants and products in chemical reactions.
By understanding this stoichiometric relationship, we can see that 2 moles of C鈧侶鈧� yield 4 moles of CO鈧�.
For example, using this ratio, we calculate that when 1 mole of acetylene reacts, it will produce 2 moles of carbon dioxide.
This fundamental relationship allows chemists and students alike to predict how much product can be formed from a given amount of reactant, and is vital for both practical applications and theoretical calculations.