Jan. 31 Chemistry update and homework due Feb. 7

Hi folks,

I'm sorry it took some time for me to get this out to you.  I wanted to take the time to grade your quizzes so that I could see where folks are.

We worked more with moles and stoichiometry today.  This has proven to be a difficult topic so we're continuing to work with it.  To try to make the concept a bit more concrete, I had the students use moles to count the number of molecules in a jar of air, a jar of salt and a jar of sugar.  

For homework this week, do the following questions.  The answers are included at the bottom.  PLEASE take the time to check your answers and make sure you understand how to get these right.   These are the kinds of questions that will keep coming up in quiz after quiz.  It behooves you to master this material.  :)

1.  Balance these reactions and tell me what kinds of reactions they are.

a.  C₆H₁₂O₆(s) +   O₂ (g)  -->   CO₂(g) +   H₂O

b.  H₂ (g) +   O₂ (g)   -->    H₂O (l)

c.  NaCl (s) +   AgNO₃ (aq) -->    AgCl (s) +   NaNO₃ (aq)

d.  HBr (l)  +    Ca(OH)2 (s)  -->    H₂O  +   CaBr₂ (aq)

e.  NaHPO₄ (s)  -->   Na (s)   +  H₂  +  P   +  O₂

2. Which atom in the following pairs would be more electronegative?

a.  V & Ge    b. Li & Rb  c.  Pb & Re

3. Which atom in the following pairs would be have larger radius?

a. Be & Sr   b. Hg & Ta  c.  Zn & Kr

4. Name the following polyatomic ions.

a. HSO3-

b. HCO3-

c. OH-

5.  Give the formula for the following polyatomic ions. (Don't forget the charges.)

a. Sulfate

b. Carbonate

c. Ammonium

6.  Write the formulas for the following compounds.  Give their molar mass as well.

a. Sodium Phosphide

b.  Ammonium Sulfate

c. Iron (III) oxide

d.  Copper (I) Carbonate

e. Cr(NO2)3

f.  Silicon difluoride

g. Diphosphorous trichloride

7.  Name the following compounds

a. NH4OH

b. Be2SO4

c. N2H4

d. CBr4

8. Draw Cr(NO2)3

9.  N2O3  +  H2O   -->  HNO2

a.  Balance the equation.

b.  At STP how many liter of dinitrogen trioxide react to produce 36.98g of nitrous acid?

c.  How many molecules of water react with 17.3 L of dinitrogen trioxide (at STP)?

10.  How many atoms of K₂CrO₄ are there in .87 moles of the compound?

11.  If you have 96 liters of CO₂, how many grams do you have?

12.  If you have 23 x 10²³ atoms of NaCl how many grams do you have?

1. a.  C₆H₁₂O₆(s) +  6O₂ (g)  -->  6CO₂(g) +  6H₂O

b.  2H₂ (g) +   O₂ (g)   -->    2H₂O (l)

c.  2HBr (l)  +    Ca(OH)2 (s)  -->    2H₂O  +   CaBr₂ (aq)

2. Which atom in the following pairs would be more electronegative?  Answers in bold.

a.  V & Ge    b. Li & Rb  c.  Pb & Re

3. Which atom in the following pairs would be have larger radius?

a. Be & Sr   b. Hg & Ta  c.  Zn & Kr

4. Name the following polyatomic ions.

a. HSO3-  Hydrogen Sulfite

b. HCO3- Hydrogen Carbonate

c. OH- Hydroxide 

5.  Give the formula for the following polyatomic ions. (Don't forget the charges.)

a. Sulfate 

SO42-

b. Carbonate 

CO32-

c. Ammonium

 

NH4+

6.  Write the formulas for the following compounds.  Give their molar mass as well.

a. Sodium Phosphide Na3P

b.  Ammonium Sulfate  (NH4)2(SO4)

c. Iron (III) oxide  Fe2O3

d.  Copper (I) Carbonate Cu2(CO3)

e.  Silicon difluoride  SiF2

f. Diphosphorous trichloride  P2Cl3

7.  Name the following compounds

a. NH4OH  Ammonium Hydroxide

b. Be2SO4  Beryllium Sulfate 

c. N2H4 Dinitrogen Tetrahydride

d. CBr4 Carbon Tetrabromide

8.  N2O3  +  H2O   -->  HNO2

a.  Balance the equation.  

 N2O3  +  H2O   -->  2HNO2

b.  At STP how many liter of dinitrogen trioxide react to produce 36.98g of nitrous acid?

9l

c.  How many molecules of water react with 17.3 L of dinitrogen trioxide (at STP)?

4.65 x 10^23

10.  How many atoms of K₂CrO₄ are there in .87 moles of the compound?

5.24x10^23

11.  If you have 96 liters of CO₂, how many grams do you have?

189.2g