SCI 131 WEEK QUIZ QUESTIONS AND ANSWERS Lesson 05 - Week 05 Quiz

Part 1 of 1 - 100.0 Points Question 1 of 25 `Sodium and chlorine are very dangerous by themselves. However, when we combine them together in a chemical 4.0 Points reaction, we eat it--it's table salt: 2Na + Cl2 → 2NaCl. If I want to make 50.0 g of my own salt (because I can and that's how I roll), how much elemental sodium would I need? NOTE: All numbers located immediately after elemental symbols should be considered subscripts. A. 50.0 g B. 100.0 g C. 22.99 D. 19.67 g E. not enough information Feedback: Good. See section 8.6 Question 2 of 25 `If you ever watch a shuttle launch, you will see what looks like a crazy amount of smoke at the take off. But if you get up4.0 Points closer to the launch pad afterwards, you will see a bunch of ice! The reason is because hydrogen gas is the fuel, and it is being combusted with oxygen gas to form water: 2H2 + O2 → 2H2O. We will learn later why ice forms here even though it is so warm. But for now, what would be the total mass in grams of water (ice) if you completely combusted 200.0 kilograms of hydrogen gas? NOTE: All numbers located immediately after elemental symbols should be considered subscripts. A. 1784 kg B. 1802 kg C. 3604 kg D. 200.0 kg E. not enough information Feedback: Good. See section 8.6 Question 3 of 25 `Let's just consider the concept of stoichiometry without any confusing chemicals. Here is a generic equation: 2A + 6B 4.0 Points → 3C. If you mix 4 units of A and 11 units of B, what would be the theoretical yield of C? A. 8 B. 3 C. 6 D. 5.5 E. none of the above Feedback: Good. See section 8.5 Question 4 of 25 `Sodium and chlorine are very dangerous by themselves. However, when we combine them together in a chemical 4.0 Points reaction, we eat it--it's table salt: 2Na + Cl2 → 2NaCl. If I have 5.00 mol of chlorine gas and excess sodium, how many moles if table salt could I theoretically make? NOTE: All numbers located immediately after elemental symbols should be considered subscripts. A. 5.00 B. 10.0 C. 1.0 D. 2.00 E. not enough information Feedback: Good. See section 8.6 Question 5 of 25 `If carbon dioxide is streamed over silicon in the right conditions, you can produce solid carbon and silicon dioxide: 4.0 Points CO2 + Si → SiO2 + C. Suppose if you stream 1.50 mole of CO2 over 1.50 mole of Si. Which of the choices below represent a true statement about this reaction? NOTE: All numbers located immediately after elemental symbols should be considered subscripts. A. The CO2 is the limiting reactant. B. The SiO2 is the limiting reactant. C. You have equal stoichiometric amounts of reactants D. The Si is the limiting reactant. E. none of these are true Feedback: Good. See section 8.6 Question 6 of 25 `Magnesium oxidizes pretty easily via the reaction 2 Mg + O2 → 2 MgO. The reaction has a △H rxn = -1203 kJ. How much heat (in kJ) is released when you completely react 3.000 moles of O2? A. -401.0 kJ B. -1203 kJ C. -2406 kJ 4.0 Points D. -3609 kJ Feedback: Good. See section 8.7 Question 7 of 25 Suppose you were tasked with producing some nitrogen monoxide (a.k.a. nitric oxide). I'm sure this is often requested4.0 Points of you. You can do it by combusting ammonia (be careful!). The equation would be as follows: 4NH3 + 5O 2→ 4NO + 6H2O. If you form 2 mol of water, how much NO forms? A. 1.33 mol. B. 2.57 mol. C. 2.29 mol. D. 3.86 mol. Feedback: Good. See section 8.6 Question 8 of 25 `Determining the limiting reactant is an extremely important concept in chemistry. To do this, you need to know all of the following information EXCEPT 4.0 Points A. the molar mass of each reactant present. B. the coefficient of each reactant in a balanced equation.