Calculating Amounts of Reactants and Products Solid lithium hydroxide is used in space vehicles to remove the carbon dioxide gas exhaled by astronauts. The hydroxide reacts with the carbon dioxide to form solid lithium carbonate and liquid water. How many grams of carbon dioxide can be absorbed by 1.00 g of lithium hydroxide? Methanol, CH3OH, reacts with oxygen from air in a combustion reaction to form water and carbon dioxide. What mass of water is produced in the combustion of 23.6 g of methanol?
Answer : Step 1 1 Balance the equation for the reaction. 2 Convert the known mass of the reactant or product to moles of that substance. 3 Use the balanced equation to set up the appropriate mole ratios. 4 Use the appropriate mole ratios to calculate the number of moles of the desired reactant or product. 5 Convert from moles back to grams if required by the problem The LiOH can absorb 919.9 g of carbon dioxide. Step 2 Explanation: The balanced equation is 2LiOH+CO2Li2CO3+H2O You must make the following conversions: mass of LiOHmoles of LiOHmoles of CO2mass of CO2 1.00×103g LiOH×1 mol LiOH/23.95g LiOH=41.8 mol LiOH 41.8mol LiOH×1 mol CO2/2 mol LiOH=20.9 mol CO2 20.9mol CO2×44.01 g CO2/1mol CO2= 919 g CO2. Step 3 The combustion reaction of methanol is represented by the following balanced chemical equation. CH3OH (l)+2O2(g)CO2(g)+2H2O(g). Calculate the number of moles of methanol in 23.6g as follows: Number of moles of propane =weight of propane/molecular mass of propane =23.6 g /32.0g. =5.9/8g.