Questions asked by Michaela

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• Write the net ionic equation that describes the reaction that occurs when a solution of barium nitrate is added to a flask containing sulfate ions?
  
• What would be the net ionic equation of a solution of sodium acetate and a solution of calcium chloride and a solution of mercury(I) nitrate are mixed together?
  
• How do you write the balanced molecular and net ionic equations for the reaction between aluminum metal and silver nitrate? What are the oxidation and reduction half-reactions?
  
• Using the balanced equation shown below, what is the mass of C3H8 that must react in order to release 1.25×10^6 kJ of heat? ΔHrxn = –2219.9 kJ
  
• Imagine that hydrogen molecules (#H_2#) and oxygen molecules (#O_2#) decided to have a race. if the temperature was the same for both gases, which gas would win the race? Why?
  
• Adding nitric acid to water is quite exothermic. What is the temperature change of 100 mL of water (d = 1.00g/mL) at 20.0°C [cp = 75.3 J/(mol·°C)] after adding 10.0 mL of concentrated HNO3(14.0M , ΔH°soln = –33.3 kJ/mol) ?
  
• Helium is found to diffuse four times more rapidly than an unknown gas. What is the approximate molar mass of the unknown gas?
  
• What is the ratio predicted from Graham's law for rates of diffusion for #NH_3#/#HCl# ?
  
• The flame produced by the burner of a gas (propane) grill is a blue color when enough air mixes with the propane (C3H8) to burn it completely. For every gram of propane that flows through the burner, what volume of air is needed to burn it completely?
  
• How many grams of sodium azide are needed to provide sufficient nitrogen gas to fill a 50.0 × 50.0 × 25.0 cm bag to a pressure of 1.15 atm at 25.0 °C? 
  
• A scuba diver is at a depth of 355 m, where the pressure is 36.5 atm. What should be the mole fraction of #O_2# in the gas mixture the diver breathes in order to have the same partial pressure of oxygen in his lungs as he would at sea level?
  
• The two isotopes of uranium, #""^238 U# and #""^235 U#, can be separated by effusion of the corresponding #UF_6# gases. What is the ratio (in the form of a decimal) of the RMS speed of #""^238 UF_6# to that of #""^235 UF_6# at constant temperature?
  
• A mixture of 0.166 mols of #"C"# reacted with 0.117 mols of #"O"_2# in a sealed, 10.0 L vessel at 500.0 K, producing a mixture of #"CO"# and #"CO"_2#. The reaction is: #3"C"(s)+2"O"_2​(g)-> 2"CO"(g)+"CO"_2​(g)#. What is the partial pressure of #"CO"#?
  
• A bicycle racer rides from a starting point to a turnaround marker at 10 m/s. She then rides the same route from the turnaround marker to the starting point at 16 m/s. (a) What is her average speed for the whole race? (b) What is her average velocity?
  
• An Olympic skier makes a run down a snowy hill starting at 100 m vertical distance above the ground. (a) If friction is neglected, what is the velocity of the skier at the bottom of the hill? (b) What is the velocity half way down the hill?
  
• Spiderman is standing on top of a 6-story building. He uses his webs to swing to the roof of a 1 story building (which is 3 m). What are spiderman's (a) initial energy, (b) final energy, and (c) speed when his feet touch the roof of the 1-story building?
  
• What pressure is exerted on the bottom of a 0.500 m wide by 0.900 m long gas tank that holds 50-kg of gasoline? Use 720 kg/m3 for the density of gasoline.
  
• A block of wood 0.12 m x 0.34 m x 0.43 m floats along a river with the broadest face down in the river. The wood is submerged to a depth of 0.053 m. What is the mass of the block? The density of water is 1000 kg/m3.
  
• A block weighing 5.0 N is at rest on a horizontal surface. A 1.0 N upward force is applied to the block by an attached helium filled balloon with a massless string. What are the magnitude and direction of the force of the horizontal surface on the block?