Gases and Stoichiometry

Review Ideal Gas LawReview Ideal Gas Law

Gas Law StoichiometryGas Law Stoichiometry

Ideal Gas Law

• Remember, mathematically,Remember, mathematically,

PV=nRTPV=nRT

• Where R = 8.31 LkPa/molKWhere R = 8.31 LkPa/molK

Pressure x vol. = # of moles x ideal gas constant x temp.

Ideal Gas LawIdeal Gas Law

• Now that we have talked more Now that we have talked more exhaustively about the subject of exhaustively about the subject of moles as it relates to mass, we moles as it relates to mass, we can add a new type of problem.can add a new type of problem.

Practice ProblemPractice Problem

• What volume will 12 grams of What volume will 12 grams of oxygen gas (Ooxygen gas (O22) will occupy at ) will occupy at

2525ooC and 52.7 kPa?C and 52.7 kPa?

Practice ProblemPractice Problem

• How many grams of carbon How many grams of carbon dioxide can be contained in a dioxide can be contained in a 17.8L container at 2217.8L container at 22ooC and C and 188kPa?188kPa?

Gas Stoichiometry

• Remember when we looked at chemical quantities and said that for any gas, 1 mole = 22.4L @ STP?

• Now we know that if you change the temperature and pressure, the relationship doesn’t work!

Gas Law StoichiometryGas Law Stoichiometry

• If gases are being produced or If gases are being produced or consumed in a chemical reaction, consumed in a chemical reaction, we can use stoichiometry along we can use stoichiometry along with the ideal gas law to solve with the ideal gas law to solve problems for gases NOT at problems for gases NOT at standard temperature and standard temperature and pressure.pressure.

Practice ProblemPractice Problem

• In the reaction KClOIn the reaction KClO33 KCl + O KCl + O22

38.5g of potassium chlorate are 38.5g of potassium chlorate are burned and the resultant oxygen burned and the resultant oxygen is captured at 100.7kPa and 298K. is captured at 100.7kPa and 298K. What volume of oxygen is What volume of oxygen is generated?generated?

Practice ProblemPractice Problem

• In the combustion of 25.3g In the combustion of 25.3g methane (CHmethane (CH44), the carbon ), the carbon

dioxide produced is trapped in a dioxide produced is trapped in a 31.3L container at 3131.3L container at 31ooC. What is C. What is the pressure due to carbon the pressure due to carbon dioxide in this container? dioxide in this container? (remember to write a balanced (remember to write a balanced equation)equation)

Molarity Review

• Remember, molarity is the SI Remember, molarity is the SI measure of concentration, found measure of concentration, found by taking the number of moles by taking the number of moles solute per liter of solution.solute per liter of solution.

M = (mol solute)/(L solution)M = (mol solute)/(L solution)

• Now that we have talked more Now that we have talked more exhaustively about the subject of exhaustively about the subject of moles as it relates to mass, we moles as it relates to mass, we can use it with concentration.can use it with concentration.

Practice ProblemPractice Problem

• What is the molarity of a solution What is the molarity of a solution made by adding 38.77g MgSOmade by adding 38.77g MgSO44 to to

enough water to make 0.85L enough water to make 0.85L solution?solution?

Practice ProblemPractice Problem

• How many grams of sodium How many grams of sodium nitrate are needed to make 500mL nitrate are needed to make 500mL of 2.0M solution?of 2.0M solution?