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Chemistry: The Central Science14th EditionBruce Edward Bursten, Catherine J. Murphy, H. Eugene Lemay, Matthew E. Stoltzfus, Patrick Woodward, Theodore E. Brown 7,852 solutions
Atkins Physical Chemistry10th EditionJulio de Paula, Peter Atkins 1,315 solutions Quantitative Chemical Analysis8th EditionDaniel C. Harris 921 solutions Chemistry for Engineering Students2nd EditionLawrence S. Brown, Thomas A. Holme 945 solutions Acetylene gas (C2H2) reacts with oxygen gas (O2) to produce carbon dioxide (CO2) and water vapor (H2O). How many liters of C2H2 are required to produce 75.0 L of CO2? What volume of H2O is produced? What volume of O2 is required? When making the calculations, did you need to find the number of moles? Liquid carbon disulfide (CS2) reacts with 44.8 L O2 gas to produce the gases carbon dioxide (CO2) and sulfur dioxide (SO2) What is the mass of carbon dioxide produced? What is the mass of sulfur dioxide produced? When making the calculations, did you need to find the number of moles? Cars and many other vehicles have air bags in them. In case of a collision, a reaction is triggered so that the rapid decomposition of sodium azide produces nitrogen gas, filling the air bag. If too little sodium azide is used, the air bag will not fill completely and will not protect
the person in the vehicle. Too much sodium azide could cause the formation of more gas that the bag can safely handle. If the bag breaks from the excess gas pressure, all protection is lost. Chemical reactions frequently involve both solid substances whose masses can be
measured, as well as gases, for which volume measurements are more appropriate. Stoichiometry problems of this type are called either mass-volume or volume-mass problems. \[\text{mass of given} \rightarrow \text{moles of given} \rightarrow \text{moles of unknown} \rightarrow \text{volume of unknown}\nonumber \] \[\text{volume of given} \rightarrow \text{moles of given} \rightarrow \text{moles of unknown} \rightarrow \text{mass of unknown}\nonumber \] Because both types of
problems involve a conversion from either moles of gas to volume or vice-versa, we can use the molar volume of \(22.4 \: \text{L/mol}\), provided that the conditions for the reaction are at STP. Aluminum metal reacts
rapidly with aqueous sulfuric acid to produce aqueous aluminum sulfate and hydrogen gas: \[2 \: \text{Al} \left( s \right) + 3 \ce{H_2SO_4} \left( aq \right) \rightarrow \ce{Al_2(SO_4)_3} \left( aq \right) + 3 \ce{H_2} \left( g \right)\nonumber \] Determine the volume of hydrogen gas produced at STP when a \(2.00 \: \text{g}\) piece of aluminum completely reacts. Solution: Step 1: List the known quantities and plan the problem. Known
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The grams of aluminum will first be converted to moles. Then the mole ratio will be applied to convert to moles of hydrogen gas. Finally, the molar volume of a gas will be used to convert to liters of hydrogen. \[\text{g} \: \ce{Al} \rightarrow \text{mol} \: \ce{Al} \rightarrow \text{mol} \: \ce{H_2} \rightarrow \text{L} \: \ce{H_2}\nonumber \] Step 2: Solve. \[2.00 \: \text{g} \: \ce{Al} \times \frac{1 \: \text{mol} \: \ce{Al}}{26.98 \: \text{g} \: \ce{Al}} \times \frac{3 \: \text{mol} \: \ce{H_2}}{2 \: \text{mol} \: \ce{Al}} \times \frac{22.4 \: \text{L} \: \ce{H_2}}{1 \: \text{mol} \: \ce{H_2}} = 2.49 \: \text{L} \: \ce{H_2}\nonumber \] Step 3: Think about your result. The volume result is in liters. For much smaller amounts, it may be convenient to convert to milliliters. The answer here has three significant figures. Because the molar volume is a measured quantity of \(22.4 \: \text{L/mol}\), three is the maximum number of significant figures for this type of problem. Example \(\PageIndex{2}\): Volume-Mass StoichiometryCalcium oxide is used to remove sulfur dioxide generated in coal-burning power plants, according to the following reaction. \[2 \ce{CaO} \left( s \right) + 2 \ce{SO_2} \left( g \right) + \ce{O_2} \left( g \right) \rightarrow 2 \ce{CaSO_4} \left( s \right)\nonumber \] What mass of calcium oxide is required to react completely with \(1.4 \times 10^3 \: \text{L}\) of sulfur dioxide? Solution: Step 1: List the known quantities and plan the problem. Known
Unknown
The volume of \(\ce{SO_2}\) will be converted to moles, followed by the mole ratio, and finally a conversion of moles of \(\ce{CaO}\) to grams. \[\text{L} \: \ce{SO_2} \rightarrow \text{mol} \: \ce{SO_2} \rightarrow \text{mol} \: \ce{CaO} \rightarrow \text{g} \: \ce{CaO}\nonumber \] Step 2: Solve. \[1.4 \times 10^3 \: \text{L} \: \ce{SO_2} \times \frac{1 \: \text{mol} \: \ce{SO_2}}{22.4 \: \text{L} \: \ce{SO_2}} \times \frac{2 \: \text{mol} \: \ce{CaO}}{2 \: \text{mol} \: \ce{SO_2}} \times \frac{56.08 \: \text{g} \: \ce{CaO}}{1 \: \text{mol} \: \ce{CaO}} = 3.5 \times 10^3 \: \text{g} \: \ce{CaO}\nonumber \] Step 3: Think about your result. The resultant mass could be reported as \(3.5 \: \text{kg}\), with two significant figures. Even though the 2:2 mole ratio does not mathematically affect the problem, it is still necessary for unit conversion. Summary
Review
How do you find the relationship between mass and volume?Mass – Volume Relationship (Stoichiometry). (a) M =mn i.e molar mass =massamount.. Molar volume =massamount.. (b) Molar volume =Numbersamount=NA.. (c) Avogadro's constant =L=NA=Numbersamount.. How do you convert mass to volume in stoichiometry?Mass-Volume Stoichiometry Problem. Convert mass of given to moles of given by dividing by the formula mass of the given.. Convert moles of given to moles of needed using the balanced equation.. Convert moles of needed to liters of requested using PV = nRT.. What is volume volume stoichiometry?Avogadro's hypothesis states that equal volumes of all gases at the same temperature and pressure contain the same number of gas particles. Further, one mole of any gas at standard temperature and pressure (0oC and 1atm) occupies a volume of 22.4L.
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