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The following 4 Essay questions require you to submit your work.  All work must be in your own handwriting.  The use of electronic devices, including writing tablets is not allowed.  No work= No credit.  Work must be neat and legible. If I cannot read it, you will not receive credit for it.  

A 25.0 mL sample of HBr is neutralized by reaction with 20.0 mL of 3.00 M KOH.  What is the concentration of HBr is the unknown sample? *hint- find the concentration of the base first. The answer must have the correct significant figures ( 1 pt) and unit ( 1 point) . Circle your final answer.  All work must be shown for credit. No work=no credit. All work must in your own hand-writing.  

The mixture of gas and air inside a cylinder reacts, releasing 400 kJ of total energy.  If the system does 250 kJ of work on the piston, how much energy is released as heat? 

A chemist prepares an aqueous solution of sodium hydroxide.  The solution contains 263.3 g of NaOH and has a volume of 750.0mL.  What is the molarity (moles/liter) of this solution? M=mols/L Answer with correct unit (1 point) and correct significant figures ( 1 point) All work must be shown for credit. No work=no credit. All work must in your own hand-writing.  

What is the formal charge on the oxygen atom in: CH3O   (Hint: Draw out the molecule with the correct valence electrons)

A small Oreo Dairy Queen® blizzard contains [x] kilocalories of stored chemical energy.  What is this energy in kilojoules?   1cal= 4.184 joules

Given the accompanying partial activity series, predict which of the following will react with cobalt, Co.   Zn –>Zn2+ + 2e– Fe –> Fe2+ + 2e– Co –> Co2+ + 2e– Ni –> Ni2+ + 2e– Cu –> Cu2+ + 2e–  

A neutral carbon atom has                   valence electrons.

Write the balanced net ionic equation for the reaction consisting of the two half-reactions given. Cu –> Cu2+ + 2e– Au3+ + 3e––> Au

The Lewis structure of the cyanide ion is shown here.  How many valence electrons are in this ion?  -1:C = N: