Chem 120 Unit 4 Midterm Exam-Fall term

Question: Joe conducts an experiment to test the effectiveness of a new drug for cancer. Which of the following variables would be easiest to control? Question: A mixture containing 50 grams of carbon and 75 grams of oxy ...

Question: Joe conducts an experiment to test the effectiveness of a new drug for cancer. Which of the following variables would be easiest to control? Question: A mixture containing 50 grams of carbon and 75 grams of oxygen is sealed in a flask. The total mass of the system is 225 grams. The flask is heated to cause the carbon and oxygen to react. The sealed flask is massed. What is the mass of the sealed flask? Question: Aluminum has a density of 2.7 g/cm3. What would be the mass, in g, of a block of aluminum with a volume of 15 cm3? Question: How many kilometers are in 800 m? Question: One mole is of carbon is equal to Question: The element iron (Fe) occurs naturally as four isotopes. Each of these isotopes has Question: How many neutrons are in this isotope of tin? Question: The element with the ground state electron configuration of 1s2 2s2 2p6 3s2 3p5 is Question: The number of protons in a chloride ion, Cl-, is Question: When barium reacts with iodine, barium ions, Ba2+, and iodide ions, I-, are formed. In this reaction, iodine atoms Question: Which substance has ionic bonds? Question: The name of the compound S2O3 is Question: In a nonpolar covalent bond, electrons are Question: The formula of magnesium nitride is Question: Which is the electron dot structure of nitrogen? Question: Which atom is least likely to form an ion? Question: The formula mass of CO2 is Question: How many moles of (NH4)2S are there in 75 g of (NH4)2S? Question: The molarity of a solution that contains 8.0 g of NaOH in a liter of solution is Question: How many liters of a 20% ethanol solution can you prepare by diluting 5 liters of a 40% ethanol solution? Question: A chemist makes a solution by dissolving 14 g of NaCl to a volume of 350 mL in water. What is the mass/ volume % concentration of this solution? Question: How many oxygen atoms are in the formula for iron(III) oxide? Question: The best description of the shape of a boron trifluoride (BF3) molecule is Question: Which of the following statements about molecules is correct? Question: Match the compounds with their shapes: Question: Match the ion or ground state atom to the correct number of electrons: Question: Balance the equation: C3H8 + O2 → CO2 + H2O (6 points) Question: For the balanced chemical reaction: 2 HCl + Mg(OH)2 → MgCl2 + H2 Determine the MW of MgCl2. Show your work. (3 points) Determine how many mols of HCl you would require to produce 20 grams of MgCl2. Show your work (3 points) Question: How many ml of a 8 M KBr solution are required to produce 250 ml of a 2 M KBr solution? Question: An isotope has a mass number of 67 and 39 neutrons. Determine the number of protons (2 points), number of electrons (2 points) and the the chemical symbol of this isotope (2 points). Question: Your daughter is an avid jump roper. The current brand that she uses, ACE, wears out within 1 week and has recently worn out. You want to find a brand that lasts longer. Given the recent resurgence in this sport, there are a number of manufacturers claiming to have high performance jump ropes. Teammate 1 says that brand TTT "the best!”, Teammate 2 says that brand ZZZ "is cool!", and you also found a brand BBB jump rope at the discount store. Use the scientific method to approach this scenario. Formulate a testable hypothesis (2 points). Design an experiment to test your hypothesis, and include your controls and be specific in your experimental design (4 points). Predict the experimental results that would support your hypothesis (2 points). Question: Balance the equation: C3H8 + O2 → CO2 + H2O (6 points) Question: For the balanced chemical reaction: 2 HCl + Mg(OH)2 → MgCl2 + H2 (a)Determine the MW of MgCl2. Show your work. (3 points) (b) Determine how many mols of HCl you would require to produce 20 grams of MgCl2. Show your work (3 points) Question: How many ml of a 8 M KBr solution are required to produce 250 ml of a 2 M KBr solution? Question: An isotope has a mass number of 67 and 39 neutrons. Determine the number of protons (2 points), number of electrons (2 points) and the the chemical symbol of this isotope (2 points). Question: Your daughter is an avid jump roper. The current brand that she uses, ACE, wears out within 1 week and has recently worn out. You want to find a brand that lasts longer. Given the recent resurgence in this sport, there are a number of manufacturers claiming to have high performance jump ropes. Teammate 1 says that brand TTT "the best!”, Teammate 2 says that brand ZZZ "is cool!", and you also found a brand BBB jump rope at the discount store. Use the scientific method to approach this scenario. Formulate a testable hypothesis (2 points). Design an experiment to test your hypothesis, and include your controls and be specific in your experimental design (4 points). Predict the experimental results that would support your hypothesis (2 points).