3.1: Quiz 1

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1) Consider the combustion of a candle \(\left(\mathrm{C}_{25} \mathrm{H}_{52}\right)\) with oxygen \(\left(\mathrm{O}_2\right)\) to form carbon dioxide \(\left(\mathrm{CO}_2\right)\) and water \(\left(\mathrm{H}_2 \mathrm{O}\right)\). A typical candle has \(100 \mathrm{~g}\) of \(\mathrm{C}_{25} \mathrm{H}_{52}\). Please answer the following questions:

a) (2 pts) Write the balanced reaction for the combustion of a candle (2 points).

b) (2 pts) You are in a closed room with a mole of \(\mathrm{O}_2\) molecules. If you light 5 candles, what will be the limiting reagent and how much excess (in grams) of either the \(\mathrm{O}_2\) or \(\mathrm{C}_{25} \mathrm{H}_{52}\) will remain?

2) Your student ID is made of a plastic called polyvinyl chloride. The molecular unit in this material is \(\mathrm{C}_2 \mathrm{H}_3 \mathrm{Cl}\), and for this question you can assume the card is made of only this molecule, with a density of \(1.4 \mathrm{grams} / \mathrm{cm}^3\). Please answer the following questions:

a) (1 pt) Use your \(3.091\) ruler to determine the mass of your student ID card in grams (assume a thickness of \(2 \mathrm{~mm}\) and that the card is perfectly rectangular).

b) (2 pts) How many moles of \(\mathrm{C}_2 \mathrm{H}_3 \mathrm{Cl}\) are in the ID card?

c) \(\left(2\right.\) pts) There are only 2 stable isotopes of chlorine, \({ }^{35} \mathrm{Cl}\) and \({ }^{37} \mathrm{Cl}\). What is their relative abundance?

d) (1 pt) You take all the chlorine out of your card and us it to disinfect a 100,000-gallon swimming pool which requires \(1 \mathrm{~kg}\) of \(\mathrm{Cl}\). How many ID cards do you need to disinfect the pool?