CHEM 162 - EXAM 2

Which of these lead ionic compounds will produce lead (II) ions when added to water?
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Which of these lead ionic compounds will produce lead (II) ions when added to water?
Pb(ClO4)2
What are the oxidation numbers for each element in C4HO? (Include the + or - sign, if a non-zero #.)
1/4 or 0.25
+1
-2
Given the reaction:
Co (s) + 2 HBr (aq) ---> CoBr2 (aq) + H2 (g)

Answer the questions below. Do not include states.

Write the chemical formula for one of the reactants : HBr

Which compound undergoes oxidation? Co

What is the oxidizing agent: HBr

What is the oxidation number of H in H2? 0
What is the oxidation number for sulfur in SF4?
+4
Balance the equations by inserting coefficients. Put a coefficient in EVERY blank.
1 NaH (s) + 1 H2O (l) ---> 1 NaOH (aq) + 1 H2 (g)
Solutions of sodium chloride and mercury (I) nitrate are combined. What is the net ionic equation for that reaction?
C. Hg22+(aq) + 2 Cl-(aq) ---> Hg2Cl2 (s)
How many moles of Li3N can be formed by adding 1.00 mole of nitrogen gas to 6.00 moles moles of Li?

6 Li (s) + N2 (g) ---> 2 Li3N
A. 2.00 moles Li3N
How many moles of AlF3 are in 0.230 L of a 0.110 M AlF3 solution?
A. 0.0253 moles AlF3
What are the units and labels of M in a 0.108 M NaCl solution?
B
Image: What are the units and labels of M in a 0.108 M NaCl solution?
In a titration, what is it called when the number of moles of acid equal the number of moles of base?
Equivalence point
Answer the questions below for when: 1.43 g of barium sulfate is produced when an excess amount of sodium sulfate is added to a solution containing 0.105 mol barium chloride.The balanced equation is: Na2SO4 + BaCl2 --> BaSO4 + 2 NaCl What is the desired solid product? BaSO4 What is the actual yield? 1.43 g What is the theoretical yield? 24.6 g What is the percent yield? 5.81 % Is this a good yield? (yes or no) NoSulfuric acid is a component of acid rain that forms when SO2, a pollutant, reacts with oxygen and water. According to the reaction: 2 SO2 (g) + O2 (g) + 2 H2O (l) ---> 2 H2SO4 (aq)Note: Molar masses: 64.07 SO2, 32 g/mol O2, 18.02 g/mol H2O, 98.09 g/mol H2SO4 Answer the following questions using 3 sig figs A medium-sized home produces about 20.0 Kg of SO2 pollution per year. How many moles of SO2 are produced? 3.12e2 mol SO2 How many moles of H2SO4 are produced? 3.12e2 mol H2SO4 How many Kg of H2SO4 are produced? 30.6 Kg H2SO4The label has fallen off a medicine bottle. The medicine was tested to be acidic and then was tested by titration. If 26.3 mL of 2.00 M NaOH is needed to completely neutralize 7.68 g of the medicine, what is the identity of the medicine? Assume 1 mol H+ in 1 mol acidic medicine.L-Lysine (HC6H13O2N2; MM = 146 g/mol)Consider the reaction: 2 SO2 (g) + O2 (g) ---> 2 SO3 (g)Is work being done? (yes or no) Yes What is the sign on work? +A hot piece of silver is placed in a cup of cold water. Which statement describes the relationship between qsilver and qwater?-qsilver = +qwaterWhich substance requires the least amount of energy to change temperature?TungstenFor the reaction: H2O (g) + 0.5 O2 (g) ----> H2O2 (g) ∆H° = +41.2 KJ What is the ∆H° for the reaction:4 H2O2 (g) ----> 4 H2O (g) + 2 O2 (g) ∆H° = sign - number without sign: 164 KJWhat is true about the reaction: CO2 (g) + H2O (g) ---> CH2O (g) + O2 (g) ∆H = +561 KJThe reaction is endothermic.Use standard enthalpies of formation to calculate ∆Hrxn (in KJ) for the following reaction: 2 HCl (g) + H2SO4(l) ---> SO2Cl2(g) + 2 H2O(l)ΔH°rxn = sign + number without sign: 62 KJWhat is the change to the internal energy of a system that does 275 J of work and absorbs 526 J of heat from the surroundings?sign + number without sign: 251 JA 308.7 g chunk of metal initially at 75.0oC warms 224 g of water at 15.0oC to 17.5oC. Which metal was added to the water?TungstenFormaldehyde (CH2O, MM 30.0 g/mol) is used as an antiperspirant to treat sweaty and really stinky feet. A combustion reaction of formaldehyde is shown below. CH2O (g) + O2 (g) ---> CO2 (g) + H2O (g) ∆H = -561 KJ If 2.27 g of formaldehyde is combusted, how much energy (in KJ) is produced?-42.5 KJOne tablespoon of cookie dough has a mass of 15.74 g. The cookie dough is combusted in a calorimeter whose heat capacity is 72.48 kJ/∘C. The temperature of the calorimeter rises from 22.82∘C to 24.41∘C. What is the food caloric content of the cookie dough in kilocalories (or Calories) per gram? Report your number to three significant figures.1.75 CaloriesA balloon is filled with helium gas. Which of these most accurately reflects the gas in the balloon on a molecular level? The blue spheres are helium atoms in the picture and the multiple choice answers describe the picture.Helium atoms are dispersed throughout the balloonIn 1787, the same year the US constitution was signed, Dr. Charles discovered that as he decreased the temperature of a balloon, the volume ____________.DecreasesA 2.26 L balloon of helium is at 30°C and 1.61 atm, what happens to the pressure if the volume is decreased to 1.12 L?The pressure increasesA diver breathes a heliox mixture with an oxygen mole fraction of 0.050. What must the total pressure (in atm) be for the partial pressure of oxygen to be 0.21 atm? Answer with two significant figures.4.2 atmA gas‑filled weather balloon with a volume of 52.0 L is held at ground level, where the atmospheric pressure is 758 mm Hg and the temperature is 23.5∘C. The balloon is released and rises to an altitude where the pressure is 0.0818 bar and the temperature is −7.02∘C. Calculate the weather balloon's volume, in L, at the higher altitude. The weather balloon's volume is576 LWhich noble gas will effuse the slowest?KrFor the following question, report your number to 3 significant figures. A 2.65 g sample of an unknown gas at 310 K and 1.00 atm is stored in a 2.15 L flask. What is the density of the gas?1.23 g/L gas 31.3 g/molWhich two conditions does a gas behave more like an ideal gas?low pressure, high temperatureThe _____________ is the distance from one crest to the next crest or from one trough to the next trough. The __________ is the number of wavelengths per second.wavelength, frequency