PurdueChem111.0003.Spring18.Test2

Week 5

100

Ionic bonds are held together by ___________, while covalent bonds are held together by ________

electrostatic forces, sharing electrons 

200

a nonpolar bond will form between two ___ atoms of ____ electronegativity

identical, equal

300

The ion NO^- has _____ valance electrons

12 valance electrons

400

Give the name/or formula of the compound, and charge and number of each ion that makes it up

BaCO3

Iron (III) nitrate

Barium carbonate, 1 Ba2+,, 1 CO3 2-

Fe(NO3)3, 1 Fe1+ ,, 3 NO3 1-

500

Draw the lewis structure of Chlorine gas

   _{..      ..}
:Cl - Cl:

    ^{..    ..}

Week 6

100

______ molecules have a net dipole defined by the sum of individual dipoles

polar

200

How many electron domains are in OF₂ ? Bonds?  Molecular Shape? 

 

4, 2, bent/seesaw

300

Which molecule would you predict to have the greatest dipole moment?

HCl

CH4

H2

CH3OH

HF

HF

400

What are the expected bond angles in a molecule of  CH4

109.5 degrees

500

For each molecule or ion, determine the shape and indicate whether each molecule will be polar or non-polar. You must get them all right for full points: 
1. CCl4 

2.NH3 

3. CHCl3 

4. XeF2 

5. BrF5

1.  tetrahedral, non-polar  

2.trigonal pyramidal, polar

3. tetrahedral, polar 

4. linear, non-polar

5. square pyramid, polar

Week 7

100

How many moles of eggs do you have if you have 132 dozens of eggs? 

132 dozens * (12 eggs/ 1 dozen) * ( 1 mole/ 6.02*10²³ eggs)

=2.63E-21

200

How many atoms of carbon are present in 1.000 mg of carbon?

1.000 mg * (1 g/ 1000 mg) * (1  mole/ 12.0107 g) * (6.022 x 10²³ atoms / 1 mole)

=5.014 x 10²² 

300

Which of the following has the greatest mass: 

1 mole of Sc

1 mole of Cl₂

1 mole of H₂

1 mole of Ga

all have the same mass 

1 mole of Cl₂

400

Calculate the molar mass of a compound if 0.331 mole of it has a mass of 226 g.

226 g /0.331 mol 

  = 683 g/mol

500

In the compound Cu₂(OH)₂CO₃, which element is present in the largest percent mass?

M.W: 221.1156 g/mol

Cu: (2*63.546 g/mol) / (221.1156 g/mol) = 57.4776%
C: (1*12.0107 g/mol)/ (221.1156 g/mol) = 5.4319%
O:(5*15.9994 g/mol) / (221.1156 g/mol) = 36.1788%
H: (2*1.000794 g/mol)/(221.1156 g/mol)= 0.9117%

Week 8

100

Determine the mass of 1.27 moles of Mg(OH)₂

M.W Mg(OH)2: 58.32 g/mol

(1.27 mole)*(58.32 gram/mole)

74.1 g

200

How many grams of KCl are needed to prepare 500 mL of a 0.200 M KCl solution?

M.W. of KCl= 74.6 g/mol 

Molarity= moles/ Liters 
0.200 M= (x)/ (0.5 L) 

0.1 moles * 74.6 g/mole

7.46 g

300

If I leave 750 mL of 0.50 M sodium chloride solution uncovered on a windowsill and 150 mL of the solvent evaporates, what will the new concentration of the sodium chloride solution be? 

(750 mL)*(0.50 M)=(150 mL)*(x)

0.63 M
(this is the opposite of a dilution problem but you approach the same way) 

400

2.00 L of 0.800 M NaNO3 must be prepared from a solution known to be 1.50 M in concentration. How many mL are required?

(1.50 mol/L) (x) = (0.800 mol/L) (2.00 L)

x = 1.067 L

Divide the liters by 1000 to get mL, the answer is 1070 mL (notice that it is rounded off to three sig figs)

500

A 325 mL sample of solution contains 23.3 g of CaCl₂


Calculate the molar concentration of Cl⁻ in this solution

M.W CaCl₂:  110.98 g/mole

23.3 g * (mole CaCl2/110.98 g) * (2 Cl/1 mole CaCl₂)= 0.4199

Molarity= moles/Liters = 0.4199 moles/ 0.325 L = 1.29 M Cl^- 

Lab

100

Why did we use isopropyl alcohol in our fat extraction rather than water? 

fat is nonpolar, because "like dissolves like" we needed a nonpolar solvent--isopropyl alcohol! 

200

Why is finding volume by water displacement a more accurate method? 

Because water displacement accounts for all irregularities

300

You have a ball made of an unknown material, the ball weights 3580 mg. You drop it in a graduated cylinder which previously contained 10 mL of water. After the ball is summered in the water the water line is now at 12 mL. What is the density in g/mL ? 

3.58 g/ 2 mL = 1.79 g/mL

400

For every 1 gram of soil you should add 5 mL of water. How much water should you add if you measured out 3.8 grams of soil 

3. 8 g * 5 ml water/ 1 g = 19 mL water

500

Which compound do you expect will have a higher conductivity: NaCl or C₆H₁₂O₆

NaCl>ionic>electrolyte>higher conductivity