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BASIC HOMEWORK: REVIEW CH. 1-8

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Question 1

How many protons does copper have?

Periodic Table and protons

 

Explanation

atomic number = protons = electrons

 

Question 2

How many electrons does copper have? Remember atoms are neutral.

 

Explanation

Look Above ^^^^

 

Question 3

How many neutrons does copper-63 have? Help given in feedback.

 

Explanation

neutron = atomic mass - atomic number 

neutron = 63 - 29 = 34

 

Question 4

What is the mass of 1 mol of CO2 in g?
Correct

 

Explanation

CO2 = 12 + (2 x 16) = 44g

 

Question 5

What is the mass of 5 molecules of SO3 in g?

Using Avagadro's Number

Correct

 

Explanation

1 mol = 6.02 x 1023 (Avogadro's Number).

5 molecules x ( 1 mol / 6.02 E23) x ( 80g / 1mol ) = 6.64e-22 g

 

Question 6

Correctly match the element with the property.
Metal that reacts with cold water to produce OH- and H2(g) Correct
Metal (all conduct electricity)--no reaction with water, but reacts with acid to produce H2 gas Correct
Non-metal--does not conduct electricity Correct
Noble gas--inert, stable electron configuration Correct
Semimetal--poor conductor of electricity Correct

 

Explanation

  • Na reacts to produce OH- and H2 ions    
  • Transition metal react with acid to produce H2
  • Nonmetal do not conduct electricity
  • He is a nobel gas (look at the periodic table)
  • Silicon is a common semiconductor/ semimetal

 

Question 7

What is the correct formula for aluminum sulfide?
Select one:
 Correct

 

Explanation

Al: +3

S: -2


Now cross the charges to get : Al2S3

 

Question 8

Which compound is the most ionic?

Select one:
 Correct

 

Explanation

The molecule with the greatest difference in electronegativity is the most ionic.

 

Question 9

Match properties correctly

Quantum Numbers

Indicates energy and size of orbital Correct
l=0 Correct
l=1 Correct
l=2 Correct
l=3 Correct
Number of possible electron spins for each orbital Correct

 

Explanation

Each single orbital can hold a max of 2 electrons

 

Question 10

Select the correct set of quantum mechanical numbers for an electron in an s, p, d, and f orbital. (4 correct answers.)

Allowed Combination of Quantum Numbers

Select one or more:
 Correct
 Correct
 Correct
 Correct

 

Explanation

magnetic spin can be only +1/2 or -1/2

 

Question 11

Correctly match the information for the angular momentum quantum number (l) which gives the shape of the orbital. A nodal plane is a region where the electron density is zero, that is, the probability of finding the electron there is zero.

The maximum number of electrons in an electron orbital. Correct
Spherically symmetric orbital--no nodal planes Correct
Orbital shaped like a peanut or dumbbell--one nodal plane Correct
4 of the 5 orbital shaped like a double peanut--2 nodal planes Correct
Orbital shaped like flower or fancy--3 nodal planes Correct

 

Explanation

 

Question 12

What is the ground-state electron configuration for S?

Electron Configurations

Select one:
 Correct

 

Explanation

Count from left to right. 

 

Question 13

What is the electron configuration for S2-?
Select one:
 Correct

 

Explanation

Add two addition electron on top of the original configuration


 1s22s22p63s23p4 + 2

1s22s22p63s23p6
 

Question 14

What is the electron configuration for K1+?
Select one:
 Correct

 

Explanation

Subtract an electron from the original from highest nth energy level\


1s22s22p63s23p64s1 -1

 
 

Question 15

Match atomic radius from largest to smallest.

Atomic Radius

K Correct
Al Correct
Na Correct
Ar Correct
S Correct

 

Explanation

Follow the trend

 

Question 16

Match ionization energies from smallest to largest.

Ionization Energy

K Correct
Al Correct
Na Correct
Ar Correct
S Correct

 

Explanation

Follow the trend.

 

Question 17

What is the correct formula for iron (III) oxide? 
Select one:
 Correct

 

Explanation

Fe (III)  : +3

O: -2 


Cross the charges to get 

Fe2O3
 

Question 18

Which of the following tin (IV) compounds makes sense using oxidation states and conservation of charge?

Oxidation State and Polyatomic Ions

Select one:
 Correct

 

Explanation

Tin (IV) :  +4


: -1
 

Question 19

Warmup question. How many moles of Ca(OH)2 are required to neutralize (react completely with) 0.28 moles of HCl? The balanced reaction is:

2HCl(aq) + Ca(OH)2(aq) → 2H2O(l) + CaCl2(aq)

Using Balanced Equations

Correct

 

Explanation

0.28 mol HCl x ( 1 mol  Ca(OH)2  /  2 mol HCl) = 0.14

 

Question 20

What volume in L of 0.42 M Ca(OH)2 is required neutralize 0.29 moles of HCl? The balanced reaction is:

2HCl(aq) + Ca(OH)2(aq) → 2H2O(l) + CaCl2(aq)

Using Balanced Equations II

Correct

 

Explanation

0.29 mol HCl x ( 1 mol Ca(OH)2 / 2 mol HCl ) x ( 1 L / 0.42mol Ca(OH)2) = 0.34

 

Question 21

What volume in L of chlorine at 30oC and 750 torr is required to react completely with 8.73 g aluminum:

2Al(s) + 3Cl2(g) → 2AlCl3(s) 

Calculate the moles chlorine needed (as in the previous problem), then use the ideal gas law--PV = nRT. Additional help is given in the feedback.
Correct

 

Explanation

moles Al = 8.73 g / 26.9815 g/mol=0.3236 

the ratio between Al and Cl2 is 2 : 3 

moles Cl2 required = 0.3236 x (3 / 2) = 0.485
p = 750/760 = 0.987 atm 
T = 30 + 273 = 303 K 

V = nRT/P = 0.485 x 0.08206 x 303 / .987  = 12.31

 

Question 22

The following reaction takes place at a certain elevated temperature:

Fe2O3(s) + 3CO(g) → 2Fe(l) + 3CO2(s) 

What is the percent yield of iron if 53.6 g Fe2O3 in excess CO produces 18.3 g Fe? The M.W. of Fe2O3 is 159.7 g/mol and the M.W. of CO is 28.01 g/mol. 

Recall that the percent yield is the actual yield divided by the theoretical yield times 100%. Additional help is given in the feedback.
Correct

 

Explanation

53.6g / 159.7 = .3356 mol Fe2O3 


.3356 mol Fe2O3 x ( 2 mol Fe / 1 mol Fe2O3 ) x ( 56g / 1 mol Fe) = 37.59 g

37.59 g (theoretical)

18.3 g (actual)


18.3 / 37.59 = 0.4882 x 100 = 48.82 %

 

Question 23

What is the mass percent of carbon in sugar, C12H22O11? M.W. sugar = 342 g/mol. 

Help is given in the feedback.
Correct

 

Explanation

C = 12 x 12 = 144


144/ 342 = 0.42 x 100 = 42%

 

Question 24

Analysis of 3.500 g sample of an unknown compound shows that it contains 1.400 g C, 0.235 g H, and the rest O. What is the empirical formula of this compound? 

Hint, given in feedback.
Select one:
 Correct

 

Explanation

C : 1.400 g / 12 g/mol = 0.1167 

H: 0.235 g / 1.008 g/mol = 0.2331

O : 1.865 / 16.00 g/mol = 0.1166


C :  0.1167 / 0.1166 = 1

H : 0.2331 / 0.1166 = 2

O :  0.1166/  0.1166 = 1

 

Question 25

Hemoglobin has a mass of about 67,000 g/mol. It is 0.3335% iron by mass. How many iron atoms are in a molecule of hemoglobin? 

Help is given in the feedback.
Correct

 

Explanation

67,000 g/mol x 0.003335 = 223.445 g/mol of iron

223.445g/mol  x  (1/55.85 mol/g ) = 4 atoms


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