Second exam p                             CHEM 20                        Name_____________________

1          How many moles of Ni(OH)2 are in 2.85 g of Ni(OH)2.
 
 
 
 
 
 
 
 
 
 
 
 

2          Find the molecular formula for a compound containing 25.94% nitrogen and 74.06% oxygen by mass and having a molecular weight of 432.08 g/mole.
 
 
 
 
 
 
 
 
 
 
 
 
 
 

3         Complete and balance the following equations. Write N.R. for no reaction.

Least active Au, Hg, Ag, Cu, H, Pb, Sn, Ni, Fe, Zn, Al, Mg, Na, Ca, K Most active

a Pb(NO3)2 + Cu à

b O2 + C5H10O3 à

c H3PO4 + CaHCO3 à

d Ca(ClO3)2 à

e Al(OH)3 + H2SO4 à

4       Sugar burns as in the following eqauation:

C6H12O6 + 6O2 à 6CO2 + 6H2O + 2519 kJ/mole of sugar burned

a) Is the reaction endothermic or exothermic?

b) How much energy is released to make 36.00 moles of water?
 
 
 
 

5 Calculate the number of grams of carbon in 30.0 g of glucose (C6H12O6).
 
 
 
 
 
 
 
 

6         Given the unbalanced equation:

CaCO3 + H3PO4 à CO2 +

How many grams of carbon dioxide will form when 5.00 grams of calcium carbonate are reacted with 10.00 grams of phosphoric acid?
 
 
 
 
 
7        Give the complete and shorthand electron configurations for the following:

Complete Shorthand

a) Mo _______________________________________ _______________

b) Fe+3 _______________________________________ _______________

8      a) Circle the atom with the largest atomic radius.

V, Mo, Cr, Mn, Kr

b) Circle the atom with the largest ionization energy.

V, W, Mo, Cr, Mn

c) Circle the ion with the largest radius.

S2-, Sc3+ , P3- , Ca2+ ,K+ , Cl-

9           Write the dot structures for the structures for the following compounds.

O2
NO
SO4-2
N2
BF3
NO2-

10     Given the electronegativities for the following atoms, what type of molecules do you expect; polar, nonpolar or ionic? K=.8, Cl=3.0, H=2.1 , C=2.4, Ag=1.2, F=4.0, Br=2.5

a) KCl _______ b) CCl4_______c) CHF3 ________d) HBr________e) K2CO3________

11 a) What volume of hydrogen gas will be produced if 20.0 g of aluminum is reacted with excess hydrochloric acid and the gas is at S.T.P.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

b) What will the volume of the above gas be if the pressure is decreased to 600 torr and the temperature is 100° C.