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Consider the following equation.  Cu (s) + 2 HBr (aq) –>  CuBr2 (aq)  +  H2 (g) A 100. mL solution of 0.025 M HBr that completely reacts with copper metal will produce ___ moles of hydrogen gas.

What is the pH of a 7.8 x 10-2 M KOH solution?   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.  

A 3.0 kg sample of pond water contains 3.6 mg of a pollutant.  What is the concentration of this pollutant in ppm?

A 50.0 mL sample of H2SO4 is neutralized with NaOH solution having a concentration of 2.00 M.  If 35.5 mL of NaOH are required to complete the neutralization, what is the concentration of the sulfuric acid solution? 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.  

What is the correct electronic geometry and molecular geometry around the central nitrogen in NO2-?  (Hint:  you may need to draw the molecule.)

You wish to prepare 1050.0 mL of a 3.0 M solution of NaOH by diluting a concentrated  6.0 M NaOH solution.  What volume of the concentrated solution is required to do this? hint: m1v1=m2v2 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.  

Consider the following equation.  Zn (s) + 2 HCl (aq) –>  ZnCl2 (aq)  +  H2 (g) If  0.50 moles of zinc metal completely react with hydrochloric acid how many moles of hydrogen gas will be made?

 Assume you had a [x] g block of pure iron metal that fully oxidized and the mass of the rust product produced was [y] g.  What must have been the mass of oxygen that initially reacted with pure iron? unbalanced chemical equation is : __Fe(s) + __O2 –> __Fe2O3   Write answer with one place after the decimal.

Copper metal reacts with aqueous hydrobromic acid to produce copper (II) bromide and hydrogen gas.   Cu (s) + 2 HBr (aq) –>  CuBr2 (aq)  +  H2 (g)   What volume of 2.50 M HBr is required to produce 45.0 L of hydrogen gas at a temperature of 298 K and a pressure of 1.00 atm? 

Below are a list of gases.  If 1.4 moles of each gas were placed into a 2.5 L balloon each, which balloon, after several days, will remained filled the most?  Assume that the material that makes up the balloon itself are the same.