We blow up a balloon from 5 Liters to 10 Liters and tie it off. Then we pass out from lack of oxygen. The balloon initially had 18 mol of CO2, how many moles of CO2 are in the balloon at the end? It is not 9!

Achemistry student needs to standardize a fresh solution of sodium hydroxide. he carefully weighs out of oxalic acid , a diprotic acid that can be purchased inexpensively in high purity, and dissolves it in of distilled water. the student then titrates the oxalic acid solution with his sodium hydroxide solution. when the titration reaches the equivalence point, the student finds he has used of sodium hydroxide solution. calculate the molarity of the student's sodium hydroxide solution. be sure your answer has the correct number of significant digits.