Author: Anonymous

Assign oxidation numbers to each atom of the redox equation below (9 pts – 1 pt per ON).  In addition, identify the oxidizing and reducing agents (2 pts – 1 pt per agent). Just list the oxidation numbers in order from left to right in your answer space.  You don’t need to write them as superscripts, and you don’t need to rewrite the entire redox equation over.   4 ClO3-  +  3 N2H4      —–>      6 NO  +  4 Cl-  +  6 H2O  

Which of the following elements is tetratomic in its standard state?

You find a bottle of phosphoric acid of unknown concentration in the lab stockroom.  To determine the concentration, you decide to perform a titration with 0.1388 M sodium hydroxide in the buret, starting with 25.00 mL of acid in the reaction flask along with some indicator solution.  The initial volume reading in the buret was 0.62 mL, and at the endpoint the final volume reading in the buret was 49.11 mL.  What is the concentration (in M) of the phosphoric acid solution?

Which of the following is a major product in the reaction of aqueous lithium bicarbonate and hydrochloric acid?

At a particular pressure and temperature, N2 gas effuses at a rate of 576 particles per second.  What is the effusion rate of sulfur hexafluoride gas at this same pressure and temperature?

When the math expression below is simplified, how many sig figs should the result have?

Provide the missing systematic chemical name or chemical formula for the following substances.  Spelling counts.  When entering formulas, all numbers will be assumed to be subscripts.  Include states of matter such as (g) and (aq) ONLY when the state of matter affects the name of the compound.  (1 pt each) Problem # Systematic Chemical Name Chemical Formula A [namea] C2H6 B lead (II) acetate [formulab] C [namec] Ca(NO3)2 

What is the molarity of cesium cations if 89.1 grams of cesium phosphate is dissolved in enough water to prepare 825 mL of aqueous solution?

The density of a certain object is 2.588 g/mL.  You completely submerge the object in a graduated cylinder containing 68.9 mL of water, and observe the water level rise up to 74.3 mL.  What is the mass of the object, in g?

[EXTRA CREDIT] (3 pts possible, question will show as being out of 0 pts) A hotpack is commonly a plastic bag filled with aqueous sodium acetate solution.  Upon shaking the bag, sodium acetate precipitates out of solution, releasing heat in the process to keep your hands warm.  What mass of sodium acetate must precipitate out, in order for the 50.0 mL of water in the hotpack to rise in temperature from 25.0°C to 61.3°C? The heat of crystallization of sodium acetate is -19.7 kJ/mol. Assume the density of water is 0.997 g/mL, and that all heat transfer is between the sodium acetate and the water solvent.  Assume the solution is dilute such that it has the same specific heat capacity as water. Show all work, using dimensional analysis where appropriate, and highlight your answer in a readable background color.